Date | Country | Change |
| 1986 |  Iraq | Titular Metropolitan See of Tagritum (Syriac Rite) was established |
| 1986 |  Spain | Diocese of Tarazona lost territory to Metropolitan Archdiocese of Zaragoza |
| 1986.01.09 |  Philippines | Diocese of Talibon was established (from Diocese of Tagbilaran and became suffragan of Cebu) |
| 1986.02.11 |  Italy | Diocese of Gallese was suppressed (to Diocese of Civita Castellana) |
| 1986.02.11 | Italy | Diocese of Nepi was suppressed (to Diocese of Civita Castellana) |
| 1986.02.11 | Italy | Diocese of Orte was suppressed (to Diocese of Civita Castellana) |
| 1986.02.11 | Italy | Diocese of Sutri was suppressed (to Diocese of Civita Castellana) |
| 1986.02.15 |  Brazil | Territorial Prelature of Acre e Purus was promoted as Diocese of Rio Branco |
| 1986.02.15 | Brazil | Territorial Prelature of Rondonópolis was promoted as Diocese of Rondonópolis |
| 1986.02.21 |  South Sudan | Diocese of Tombura was renamed as Diocese of Tombura–Yambio |
| 1986.03.10 |  India | Apostolic Prefecture of Jammu and Kashmir was promoted as Diocese of Jammu–Srinagar |
| 1986.03.21 | South Sudan | Diocese of Yei was established (from Diocese of Rumbek and became suffragan of Juba) |
| 1986.03.27 | Italy | Diocese of Montefiascone was suppressed (to Diocese of Viterbo) |
| 1986.03.27 | Italy | Abbacy nullius of San Martino al Monte Cimino was suppressed (to Diocese of Viterbo and united to Diocese of Viterbo) |
| 1986.03.27 | Italy | Diocese of Tuscania was suppressed (to Diocese of Viterbo) |
| 1986.04.08 |  Australia | Diocese of Broken Bay was established (from Metropolitan Archdiocese of Sydney and became suffragan of Sydney) |
| 1986.04.08 | Australia | Diocese of Parramatta was established (from Metropolitan Archdiocese of Sydney and became suffragan of Sydney) |
| 1986.04.28 | India | Diocese of Thamarasserry (Syro-Malabar Rite) was established (from Diocese of Tellicherry and became suffragan of Ernakulam) |
| 1986.05.02 |  Lebanon | Diocese of Joubbé (Maronite Rite) was established (became suffragan of Antioch) |
| 1986.05.31 |  El Salvador | Diocese of Sonsonate was established (from Diocese of Santa Ana and became suffragan of San Salvador) |
| 1986.06.09 |  Kenya | Diocese of Embu was established (from Diocese of Meru and became suffragan of Nairobi) |
| 1986.06.16 |  Argentina | Diocese of Puerto Iguazú was established (from Diocese of Posadas and became suffragan of Corrientes) |
| 1986.06.16 |  USA | Diocese of Alexandria–Shreveport was renamed as Diocese of Alexandria (lost territory to establish Diocese of Shreveport) |
| 1986.06.16 | USA | Diocese of Shreveport was established (from Diocese of Alexandria–Shreveport and became suffragan of New Orleans) |
| 1986.06.30 |  France | Apostolic Vicariate of France (Armenian Rite) was promoted as Diocese of Sainte-Croix-de-Paris (without ecclesiastical province) |
| 1986.07.14 |  Canada | Diocese of Hauterive was renamed as Diocese of Baie-Comeau |
| 1986.07.21 | Argentina,  Antarctica | Military Vicariate of Argentina was promoted as Military Ordinariate of Obispado Castrense de la Argentina |
| 1986.07.21 | Australia | Military Vicariate of Australia was promoted as Military Ordinariate of Military Ordinariate of Australia |
| 1986.07.21 |  Austria | Military Vicariate of Austria was promoted as Military Ordinariate of Katholische Militärseelsorge Österreich |
| 1986.07.21 |  Belgium | Military Vicariate of Belgium was promoted as Military Ordinariate of Bisdom bij de Krijgsmacht |
| 1986.07.21 |  Bolivia | Military Vicariate of Bolivia was promoted as Military Ordinariate of Obispado Castrense de Bolivia |
| 1986.07.21 | Brazil | Military Vicariate of Brazil was promoted as Military Ordinariate of Ordinariado Militar do Brasil |
| 1986.07.21 | Canada | Military Vicariate of Canada was promoted as Military Ordinariate of Military Ordinariate of Canada |
| 1986.07.21 |  Chile, Antarctica | Military Vicariate of Chile was promoted as Military Ordinariate of Obispado Castrense de Chile |
| 1986.07.21 |  Colombia | Military Vicariate of Colombia was promoted as Military Ordinariate of Obispado Castrense de Colombia |
| 1986.07.21 |  Dominican Republic | Military Vicariate of Dominican Republic was promoted as Military Ordinariate of Obispado Castrense de República Dominicana |
| 1986.07.21 |  Ecuador | Military Vicariate of Ecuador was promoted as Military Ordinariate of Obispado Castrense del Ecuador |
| 1986.07.21 | El Salvador | Military Vicariate of El Salvador was promoted as Military Ordinariate of Obispado Castrense en El Salvador |
| 1986.07.21 |  England,  Scotland,  Wales | Military Vicariate of Great Britain was promoted as Military Ordinariate of Bishopric of the Forces in Great Britain |
| 1986.07.21 | France | Military Vicariate of France was promoted as Military Ordinariate of Diocèse aux Armées Françaises |
| 1986.07.21 |  Germany | Military Vicariate of Jurisdiktionsbereich des Katholischen Feldpropstes was promoted as Military Ordinariate of Deutsches Militärordinariat |
| 1986.07.21 |  Indonesia | Military Vicariate of Indonesia was promoted as Military Ordinariate of Military Ordinariate of Indonesia |
| 1986.07.21 | Italy | Military Vicariate of Italy was promoted as Military Ordinariate of Ordinariato Militare per l’Italia |
| 1986.07.21 | Kenya | Military Vicariate of Kenya was promoted as Military Ordinariate of Military Ordinariate of Kenya |
| 1986.07.21 |  Netherlands | Military Vicariate of Netherlands was promoted as Military Ordinariate of Military Ordinariate of the Netherlands |
| 1986.07.21 |  New Zealand | Military Vicariate of New Zealand was promoted as Military Ordinariate of Military Ordinariate of New Zealand |
| 1986.07.21 |  Paraguay | Military Vicariate of Paraguay was promoted as Military Ordinariate of Obispado de las Fuerzas Armadas y la Policia Nacional del Paraguay |
| 1986.07.21 |  Peru | Military Vicariate of Peru was promoted as Military Ordinariate of Obispado Castrense del Perú |
| 1986.07.21 | Philippines | Military Vicariate of Philippines was promoted as Military Ordinariate of Military Ordinariate of the Philippines |
| 1986.07.21 |  Portugal | Military Vicariate of Portugal was promoted as Military Ordinariate of Ordinariato Castrense de Portugal |
| 1986.07.21 |  South Africa | Military Vicariate of South African Defence Force was promoted as Military Ordinariate of South African Defence Force |
| 1986.07.21 |  South Korea | Military Vicariate of South Korea was promoted as Military Ordinariate of Military Ordinariate of South Korea |
| 1986.07.21 | Spain | Military Vicariate of Spain was promoted as Military Ordinariate of Arzobispado Castrense de España |
| 1986.07.21 |  Uganda | Military Vicariate of Uganda was promoted as Military Ordinariate of Military Ordinariate of Uganda |
| 1986.07.21 | USA, Antarctica,  U.S. Minor Islands | Military Vicariate of United States of America was promoted as Military Ordinariate of Archdiocese for the Military Services of the United States |
| 1986.08.18 |  Saint Helena, Ascension and Tristan da Cunha | Mission sui juris of Saint Helena, Ascension and Tristan da Cunha was established (from Metropolitan Archdiocese of Cape Town) |
| 1986.08.29 | Chile | Territorial Prelature of Arica was promoted as Diocese of Arica |
| 1986.09.30 | Italy | Diocese of Acerno was suppressed (to Metropolitan Archdiocese of Salerno–Campagna–Acerno) |
| 1986.09.30 | Italy | Diocese of Acquapendente was suppressed (to Diocese of Viterbo, Acquapendente, Bagnoregio, Montefiascone, Tuscania e San Martino al Monte Cimino) |
| 1986.09.30 | Italy | Territorial Prelature of Acquaviva delle Fonti was suppressed (to Diocese of Altamura–Gravina–Acquaviva delle Fonti) |
| 1986.09.30 | Italy | Diocese of Adria was renamed as Diocese of Adria–Rovigo |
| 1986.09.30 | Italy | Diocese of Alatri was suppressed (to Diocese of Anagni–Alatri) |
| 1986.09.30 | Italy | Diocese of Ales was renamed as Diocese of Ales–Terralba (gained territory from the suppressed Diocese of Terralba) |
| 1986.09.30 | Italy | Diocese of Alghero was renamed as Diocese of Alghero–Bosa (gained territory from the suppressed Diocese of Bosa) |
| 1986.09.30 | Italy | Diocese of Alife was renamed as Diocese of Alife–Caiazzo (gained territory from the suppressed Diocese of Caiazzo) |
| 1986.09.30 | Italy | Territorial Prelature of Altamura was promoted as Diocese of Altamura–Gravina–Acquaviva delle Fonti (gained territory from Metropolitan Archdiocese of Bari e Canosa and gained territory from the suppressed Diocese of Gravina and Territorial Prelature of Acquaviva delle Fonti) |
| 1986.09.30 | Italy | Archdiocese of Amalfi was renamed as Archdiocese of Amalfi–Cava de’ Tirreni (gained territory from the suppressed Diocese of Cava de’ Tirreni) |
| 1986.09.30 | Italy | Diocese of Amelia was suppressed (to Diocese of Terni–Narni–Amelia) |
| 1986.09.30 | Italy | Diocese of Ampurias was suppressed (to establish Diocese of Tempio–Ampurias) |
| 1986.09.30 | Italy | Diocese of Anagni was renamed as Diocese of Anagni–Alatri (gained territory from the suppressed Diocese of Alatri) |
| 1986.09.30 | Italy | Metropolitan Archdiocese of Ancona was renamed as Metropolitan Archdiocese of Ancona–Osimo (gained territory from the suppressed Diocese of Osimo and lost suffragan see Osimo) |
| 1986.09.30 | Italy | Diocese of Aquino was suppressed (to Diocese of Sora–Aquino–Pontecorvo) |
| 1986.09.30 | Italy | Diocese of Arezzo was renamed as Diocese of Arezzo–Cortona–Sansepolcro (gained territory from Diocese of Montepulciano, gained territory from the suppressed Diocese of Cortona and Diocese of Sansepolcro and became suffragan of Firenze) |
| 1986.09.30 | Italy | Diocese of Ariano was renamed as Diocese of Ariano Irpino–Lacedonia (gained territory from the suppressed Diocese of Lacedonia) |
| 1986.09.30 | Italy | Diocese of Ascoli Satriano was suppressed (to Diocese of Cerignola–Ascoli Satriano) |
| 1986.09.30 | Italy | Diocese of Assisi was renamed as Diocese of Assisi–Nocera Umbra–Gualdo Tadino (gained territory from the suppressed Diocese of Nocera Umbra–Gualdo Tadino) |
| 1986.09.30 | Italy | Diocese of Atri was suppressed (to Diocese of Teramo–Atri) |
| 1986.09.30 | Italy | Diocese of Marsi was renamed as Diocese of Avezzano |
| 1986.09.30 | Italy | Diocese of Bagnoregio was suppressed (to Diocese of Viterbo, Acquapendente, Bagnoregio, Montefiascone, Tuscania e San Martino al Monte Cimino) |
| 1986.09.30 | Italy | Metropolitan Archdiocese of Bari e Canosa was renamed as Metropolitan Archdiocese of Bari–Bitonto (gained territory from the suppressed Diocese of Bitonto, lost territory to Diocese of Altamura–Gravina–Acquaviva delle Fonti and lost suffragan sees Barletta, Bisceglie, Bitonto, Giovinazzo, Monopoli, Ruvo and Terlizzi) |
| 1986.09.30 | Italy | Archdiocese of Barletta was suppressed (to Archdiocese of Trani–Barletta–Bisceglie) |
| 1986.09.30 | Italy | Diocese of Belluno was renamed as Diocese of Belluno–Feltre (gained territory from the suppressed Diocese of Feltre) |
| 1986.09.30 | Italy | Diocese of Bertinoro was suppressed (to Diocese of Forlì–Bertinoro) |
| 1986.09.30 | Italy | Diocese of Bisaccia was suppressed (to Archdiocese of Sant’Angelo dei Lombardi–Conza–Nusco–Bisaccia) |
| 1986.09.30 | Italy | Diocese of Bisceglie was suppressed (to Archdiocese of Trani–Barletta–Bisceglie) |
| 1986.09.30 | Italy | Diocese of Bisignano was suppressed (to Archdiocese of Cosenza–Bisignano) |
| 1986.09.30 | Italy | Diocese of Bitonto was suppressed (to Metropolitan Archdiocese of Bari–Bitonto) |
| 1986.09.30 | Italy | Diocese of Bobbio–San Colombano was suppressed (to Metropolitan Archdiocese of Genova–Bobbio) |
| 1986.09.30 | Italy | Diocese of Bosa was suppressed (to Diocese of Alghero–Bosa) |
| 1986.09.30 | Italy | Diocese of Bova was suppressed (to Metropolitan Archdiocese of Reggio Calabria–Bova) |
| 1986.09.30 | Italy | Diocese of Bovino was suppressed (to Metropolitan Archdiocese of Foggia–Bovino) |
| 1986.09.30 | Italy | Archdiocese of Brindisi was renamed as Archdiocese of Brindisi–Ostuni (gained territory from the suppressed Diocese of Ostuni) |
| 1986.09.30 | Italy | Diocese of Brugnato was suppressed (to Diocese of La Spezia–Sarzana–Brugnato) |
| 1986.09.30 | Italy | Diocese of Cagli was suppressed (to Diocese of Fano–Fossombrone–Cagli–Pergola) |
| 1986.09.30 | Italy | Diocese of Caiazzo was suppressed (to Diocese of Alife–Caiazzo) |
| 1986.09.30 | Italy | Diocese of Calvi was suppressed (to Diocese of Teano–Calvi) |
| 1986.09.30 | Italy | Archdiocese of Camerino was renamed as Archdiocese of Camerino–San Severino Marche (gained territory from the suppressed Diocese of San Severino and became suffragan of Fermo) |
| 1986.09.30 | Italy | Diocese of Campagna was suppressed (to Metropolitan Archdiocese of Salerno–Campagna–Acerno) |
| 1986.09.30 | Italy | Diocese of Cariati was suppressed (to Archdiocese of Rossano–Cariati) |
| 1986.09.30 | Italy | Diocese of Castellammare di Stabia was suppressed (to Archdiocese of Sorrento–Castellammare di Stabia) |
| 1986.09.30 | Italy | Archdiocese of Catanzaro was renamed as Archdiocese of Catanzaro–Squillace (gained territory from Diocese of Nicastro and gained territory from the suppressed Diocese of Squillace) |
| 1986.09.30 | Italy | Diocese of Cava de’ Tirreni was suppressed (to Archdiocese of Amalfi–Cava de’ Tirreni) |
| 1986.09.30 | Italy | Diocese of Cerignola was renamed as Diocese of Cerignola–Ascoli Satriano (gained territory from the suppressed Diocese of Ascoli Satriano) |
| 1986.09.30 | Italy | Diocese of Telese was renamed as Diocese of Cerreto Sannita–Telese–Sant’Agata de’ Goti (gained territory from the suppressed Diocese of Sant’Agata de’ Goti) |
| 1986.09.30 | Italy | Diocese of Cervia was suppressed (to Metropolitan Archdiocese of Ravenna–Cervia) |
| 1986.09.30 | Italy | Diocese of Cesena was renamed as Diocese of Cesena–Sarsina (gained territory from the suppressed Diocese of Sarsina) |
| 1986.09.30 | Italy | Metropolitan Archdiocese of Chieti was renamed as Metropolitan Archdiocese of Chieti–Vasto (gained territory from the suppressed Diocese of Vasto and lost suffragan see Ortona) |
| 1986.09.30 | Italy | Diocese of Chiusi was suppressed (to Diocese of Montepulciano–Chiusi–Pienza) |
| 1986.09.30 | Italy | Diocese of Cingoli was suppressed (to Diocese of Macerata–Tolentino–Recanati–Cingoli–Treia) |
| 1986.09.30 | Italy | Diocese of Città della Pieve was suppressed (to Metropolitan Archdiocese of Perugia–Città della Pieve) |
| 1986.09.30 | Italy | Diocese of Civitavecchia was renamed as Diocese of Civitavecchia–Tarquinia (gained territory from the suppressed Diocese of Tarquinia) |
| 1986.09.30 | Italy | Diocese of Civita–Tempio was suppressed (to establish Diocese of Tempio–Ampurias) |
| 1986.09.30 | Italy | Diocese of Colle di Val d’Elsa was suppressed (to Metropolitan Archdiocese of Siena–Colle di Val d’Elsa–Montalcino) |
| 1986.09.30 | Italy | Diocese of Comacchio was suppressed (to Archdiocese of Ferrara–Comacchio and lost title of Pomposa) |
| 1986.09.30 | Italy | Diocese of Conversano was renamed as Diocese of Conversano–Monopoli (gained territory from the suppressed Diocese of Monopoli) |
| 1986.09.30 | Italy | Archdiocese of Conza was suppressed (to Archdiocese of Sant’Angelo dei Lombardi–Conza–Nusco–Bisaccia) |
| 1986.09.30 | Italy | Diocese of Cortona was suppressed (to Diocese of Arezzo–Cortona–Sansepolcro) |
| 1986.09.30 | Italy | Archdiocese of Cosenza was renamed as Archdiocese of Cosenza–Bisignano (gained territory from Diocese of Nicastro and gained territory from the suppressed Diocese of Bisignano) |
| 1986.09.30 | Italy | Diocese of Crotone was promoted as Archdiocese of Crotone–Santa Severina (gained territory from the suppressed Archdiocese of Santa Severina) |
| 1986.09.30 | Italy | Diocese of Fabriano was renamed as Diocese of Fabriano–Matelica (gained territory from the suppressed Diocese of Matelica) |
| 1986.09.30 | Italy | Diocese of Faenza was renamed as Diocese of Faenza–Modigliana (gained territory from the suppressed Diocese of Modigliana) |
| 1986.09.30 | Italy | Diocese of Fano was renamed as Diocese of Fano–Fossombrone–Cagli–Pergola (gained territory from the suppressed Diocese of Cagli, Diocese of Fossombrone and Diocese of Pergola and became suffragan of Urbino–Urbania–Sant’Angelo in Vado) |
| 1986.09.30 | Italy | Diocese of Feltre was suppressed (to Diocese of Belluno–Feltre) |
| 1986.09.30 | Italy | Diocese of Ferentino was suppressed (to Diocese of Frosinone–Veroli–Ferentino) |
| 1986.09.30 | Italy | Archdiocese of Ferrara was renamed as Archdiocese of Ferrara–Comacchio (gained territory from the suppressed Diocese of Comacchio and gained title of Pomposa) |
| 1986.09.30 | Italy | Metropolitan Archdiocese of Foggia was renamed as Metropolitan Archdiocese of Foggia–Bovino (gained territory from Archdiocese of Manfredonia, gained territory from the suppressed Diocese of Bovino and lost suffragan sees Ascoli Satriano, Troia and Vieste) |
| 1986.09.30 | Italy | Diocese of Forlì was renamed as Diocese of Forlì–Bertinoro (gained territory from the suppressed Diocese of Bertinoro and Diocese of Modigliana) |
| 1986.09.30 | Italy | Diocese of Fossombrone was suppressed (to Diocese of Fano–Fossombrone–Cagli–Pergola) |
| 1986.09.30 | Italy | Diocese of Veroli–Frosinone was renamed as Diocese of Frosinone–Veroli–Ferentino (gained territory from the suppressed Diocese of Ferentino) |
| 1986.09.30 | Italy | Diocese of Gallipoli was suppressed (to Diocese of Nardò–Gallipoli) |
| 1986.09.30 | Italy | Metropolitan Archdiocese of Genova was renamed as Metropolitan Archdiocese of Genova–Bobbio (gained territory from the suppressed Diocese of Bobbio–San Colombano and lost suffragan sees Bobbio–San Colombano, Brugnato and Noli) |
| 1986.09.30 | Italy | Diocese of Giovinazzo was suppressed (to Diocese of Molfetta–Ruvo–Giovinazzo–Terlizzi) |
| 1986.09.30 | Italy | Metropolitan Archdiocese of Gorizia e Gradisca was renamed as Metropolitan Archdiocese of Gorizia (lost territory to establish Titular Archiepiscopal See of Gradisca) |
| 1986.09.30 | Italy | Titular Archiepiscopal See of Gradisca was restored (from Metropolitan Archdiocese of Gorizia e Gradisca) |
| 1986.09.30 | Italy | Diocese of Gravina was suppressed (to Diocese of Altamura–Gravina–Acquaviva delle Fonti) |
| 1986.09.30 | Italy | Diocese of Guastalla was suppressed (to Diocese of Reggio Emilia–Guastalla) |
| 1986.09.30 | Italy | Diocese of Irsina was suppressed (to Archdiocese of Matera–Irsina) |
| 1986.09.30 | Italy | Diocese of Isernia was renamed as Diocese of Isernia–Venafro (gained territory from the suppressed Diocese of Venafro) |
| 1986.09.30 | Italy | Diocese of La Spezia was renamed as Diocese of La Spezia–Sarzana–Brugnato (gained territory from the suppressed Diocese of Brugnato and Diocese of Sarzana) |
| 1986.09.30 | Italy | Diocese of Lacedonia was suppressed (to Diocese of Ariano Irpino–Lacedonia) |
| 1986.09.30 | Italy | Diocese of Nicastro was renamed as Diocese of Lamezia Terme (lost territory to Archdiocese of Catanzaro–Squillace, Archdiocese of Cosenza–Bisignano and Diocese of Mileto–Nicotera–Tropea) |
| 1986.09.30 | Italy | Archdiocese of Lanciano was renamed as Archdiocese of Lanciano–Ortona (gained territory from the suppressed Diocese of Ortona) |
| 1986.09.30 | Italy | Diocese of Ogliastra was renamed as Diocese of Lanusei |
| 1986.09.30 | Italy | Diocese of Larino was suppressed (to Diocese of Termoli–Larino) |
| 1986.09.30 | Italy | Diocese of Terracina–Latina was renamed as Diocese of Latina–Terracina–Sezze–Priverno (gained territory from the suppressed Diocese of Priverno and Diocese of Sezze) |
| 1986.09.30 | Italy | Diocese of Lipari was suppressed (to Metropolitan Archdiocese of Messina–Lipari–Santa Lucia del Mela) |
| 1986.09.30 | Italy | Diocese of Gerace–Locri was renamed as Diocese of Locri–Gerace |
| 1986.09.30 | Italy | Diocese of Lucera was renamed as Diocese of Lucera–Troia (gained territory from the suppressed Diocese of Troia and lost territory to Diocese of San Severo) |
| 1986.09.30 | Italy | Diocese of Macerata was renamed as Diocese of Macerata–Tolentino–Recanati–Cingoli–Treia (gained territory from the suppressed Diocese of Cingoli, Diocese of Recanati, Diocese of Tolentino and Diocese of Treia) |
| 1986.09.30 | Italy | Archdiocese of Manfredonia was renamed as Archdiocese of Manfredonia–Vieste (gained territory from the suppressed Diocese of Vieste and lost territory to Metropolitan Archdiocese of Foggia–Bovino and Diocese of San Severo) |
| 1986.09.30 | Italy | Diocese of Marsico Nuovo was suppressed (to Metropolitan Archdiocese of Potenza–Muro Lucano–Marsico Nuovo) |
| 1986.09.30 | Italy | Diocese of Apuania was renamed as Diocese of Massa |
| 1986.09.30 | Italy | Diocese of Matelica was suppressed (to Diocese of Fabriano–Matelica) |
| 1986.09.30 | Italy | Archdiocese of Matera was renamed as Archdiocese of Matera–Irsina (gained territory from the suppressed Diocese of Irsina) |
| 1986.09.30 | Italy | Diocese of Melfi was renamed as Diocese of Melfi–Rapolla–Venosa (gained territory from the suppressed Diocese of Rapolla and Diocese of Venosa) |
| 1986.09.30 | Italy | Metropolitan Archdiocese of Messina was renamed as Metropolitan Archdiocese of Messina–Lipari–Santa Lucia del Mela (gained territory from the suppressed Diocese of Lipari, Territorial Prelature of Santa Lucia del Mela and Territorial Abbacy of Santissimo Salvatore and gained title of Santissimo Salvatore) |
| 1986.09.30 | Italy | Diocese of Mileto was renamed as Diocese of Mileto–Nicotera–Tropea (gained territory from Diocese of Nicastro, gained territory from the suppressed Diocese of Nicotera and Diocese of Tropea, lost territory to Diocese of Oppido Mamertina–Palmi and became suffragan of Reggio Calabria–Bova) |
| 1986.09.30 | Italy | Metropolitan Archdiocese of Modena was renamed as Metropolitan Archdiocese of Modena–Nonantola (gained territory from the suppressed Abbacy nullius of Nonantola, lost title of Nonantola and lost suffragan sees Guastalla and Nonantola) |
| 1986.09.30 | Italy | Diocese of Modigliana was suppressed (to Diocese of Faenza–Modigliana and Diocese of Forlì–Bertinoro) |
| 1986.09.30 | Italy | Diocese of Molfetta was renamed as Diocese of Molfetta–Ruvo–Giovinazzo–Terlizzi (gained territory from the suppressed Diocese of Giovinazzo, Diocese of Ruvo and Diocese of Terlizzi) |
| 1986.09.30 | Italy | Diocese of Monopoli was suppressed (to Diocese of Conversano–Monopoli) |
| 1986.09.30 | Italy | Diocese of Montalcino was suppressed (to Metropolitan Archdiocese of Siena–Colle di Val d’Elsa–Montalcino) |
| 1986.09.30 | Italy | Diocese of Montalto was suppressed (to Diocese of San Benedetto del Tronto–Ripatransone–Montalto) |
| 1986.09.30 | Italy | Diocese of Montepulciano was renamed as Diocese of Montepulciano–Chiusi–Pienza (gained territory from the suppressed Diocese of Chiusi and Diocese of Pienza, lost territory to Diocese of Arezzo–Cortona–Sansepolcro and became suffragan of Siena–Colle di Val d’Elsa–Montalcino) |
| 1986.09.30 | Italy | Diocese of Muro Lucano was suppressed (to Metropolitan Archdiocese of Potenza–Muro Lucano–Marsico Nuovo) |
| 1986.09.30 | Italy | Diocese of Nardò was renamed as Diocese of Nardò–Gallipoli (gained territory from the suppressed Diocese of Gallipoli) |
| 1986.09.30 | Italy | Diocese of Narni was suppressed (to Diocese of Terni–Narni–Amelia) |
| 1986.09.30 | Italy | Diocese of Nicotera was suppressed (to Diocese of Mileto–Nicotera–Tropea) |
| 1986.09.30 | Italy | Diocese of Nocera de’ Pagani was renamed as Diocese of Nocera Inferiore–Sarno (gained territory from the suppressed Diocese of Sarno) |
| 1986.09.30 | Italy | Diocese of Nocera Umbra–Gualdo Tadino was suppressed (to Diocese of Assisi–Nocera Umbra–Gualdo Tadino) |
| 1986.09.30 | Italy | Diocese of Noli was suppressed (to Diocese of Savona–Noli) |
| 1986.09.30 | Italy | Abbacy nullius of Nonantola was suppressed (to Metropolitan Archdiocese of Modena–Nonantola and no longer united) |
| 1986.09.30 | Italy | Diocese of Norcia was suppressed (to Archdiocese of Spoleto–Norcia) |
| 1986.09.30 | Italy | Diocese of Nusco was suppressed (to Archdiocese of Sant’Angelo dei Lombardi–Conza–Nusco–Bisaccia) |
| 1986.09.30 | Italy | Diocese of Ortona was suppressed (to Archdiocese of Lanciano–Ortona) |
| 1986.09.30 | Italy | Diocese of Orvieto was renamed as Diocese of Orvieto–Todi (gained territory from the suppressed Diocese of Todi) |
| 1986.09.30 | Italy | Diocese of Osimo was suppressed (to Metropolitan Archdiocese of Ancona–Osimo) |
| 1986.09.30 | Italy | Diocese of Ostuni was suppressed (to Archdiocese of Brindisi–Ostuni) |
| 1986.09.30 | Italy | Diocese of Pergola was suppressed (to Diocese of Fano–Fossombrone–Cagli–Pergola) |
| 1986.09.30 | Italy | Metropolitan Archdiocese of Perugia was renamed as Metropolitan Archdiocese of Perugia–Città della Pieve (gained territory from the suppressed Diocese of Città della Pieve and lost suffragan sees Città della Pieve and Nocera Umbra–Gualdo Tadino) |
| 1986.09.30 | Italy | Diocese of Pienza was suppressed (to Diocese of Montepulciano–Chiusi–Pienza) |
| 1986.09.30 | Italy | Diocese of Sovana–Pitigliano–Orbetello was renamed as Diocese of Pitigliano–Sovana–Orbetello |
| 1986.09.30 | Italy | Diocese of Policastro was suppressed (to Diocese of Teggiano–Policastro) |
| 1986.09.30 | Italy | Diocese of Pontecorvo was suppressed (to Diocese of Sora–Aquino–Pontecorvo) |
| 1986.09.30 | Italy | Diocese of Porto e Santa Rufina was renamed as Diocese of Porto–Santa Rufina |
| 1986.09.30 | Italy | Metropolitan Archdiocese of Potenza was renamed as Metropolitan Archdiocese of Potenza–Muro Lucano–Marsico Nuovo (gained territory from the suppressed Diocese of Marsico Nuovo and Diocese of Muro Lucano and lost suffragan sees Marsico Nuovo, Muro Lucano, Rapolla and Venosa) |
| 1986.09.30 | Italy | Diocese of Priverno was suppressed (to Diocese of Latina–Terracina–Sezze–Priverno) |
| 1986.09.30 | Italy | Diocese of Rapolla was suppressed (to Diocese of Melfi–Rapolla–Venosa) |
| 1986.09.30 | Italy | Metropolitan Archdiocese of Ravenna was renamed as Metropolitan Archdiocese of Ravenna–Cervia (gained territory from the suppressed Diocese of Cervia and lost suffragan sees Cervia and Sarsina) |
| 1986.09.30 | Italy | Diocese of Recanati was suppressed (to Diocese of Macerata–Tolentino–Recanati–Cingoli–Treia) |
| 1986.09.30 | Italy | Metropolitan Archdiocese of Reggio Calabria was renamed as Metropolitan Archdiocese of Reggio Calabria–Bova (gained territory from the suppressed Diocese of Bova, lost suffragan sees Cariati, Nicotera, Squillace and Tropea and gained suffragan sees Rossano–Cariati and Mileto–Nicotera–Tropea) |
| 1986.09.30 | Italy | Diocese of Reggio Emilia was renamed as Diocese of Reggio Emilia–Guastalla (gained territory from the suppressed Diocese of Guastalla) |
| 1986.09.30 | Italy | Archdiocese of Rossano was renamed as Archdiocese of Rossano–Cariati (gained territory from the suppressed Diocese of Cariati and became suffragan of Reggio Calabria–Bova) |
| 1986.09.30 | Italy | Diocese of Ruvo was suppressed (to Diocese of Molfetta–Ruvo–Giovinazzo–Terlizzi) |
| 1986.09.30 | Italy | Diocese of Sabina e Poggio Mirteto was renamed as Diocese of Sabina–Poggio Mirteto |
| 1986.09.30 | Italy | Metropolitan Archdiocese of Salerno was renamed as Metropolitan Archdiocese of Salerno–Campagna–Acerno (gained territory from the suppressed Diocese of Acerno and Diocese of Campagna and lost suffragan sees Acerno, Cava de’ Tirreni, Policastro and Sarno) |
| 1986.09.30 | Italy | Diocese of Ripatransone–San Benedetto del Tronto was renamed as Diocese of San Benedetto del Tronto–Ripatransone–Montalto (gained territory from the suppressed Diocese of Montalto) |
| 1986.09.30 | Italy | Diocese of San Severino was suppressed (to Archdiocese of Camerino–San Severino Marche) |
| 1986.09.30 | Italy | Diocese of Sansepolcro was suppressed (to Diocese of Arezzo–Cortona–Sansepolcro) |
| 1986.09.30 | Italy | Territorial Prelature of Santa Lucia del Mela was suppressed (to Metropolitan Archdiocese of Messina–Lipari–Santa Lucia del Mela) |
| 1986.09.30 | Italy | Archdiocese of Santa Severina was suppressed (to Archdiocese of Crotone–Santa Severina) |
| 1986.09.30 | Italy | Territorial Abbacy of Santissimo Salvatore (Italo-Albanese Rite) was suppressed (to Metropolitan Archdiocese of Messina–Lipari–Santa Lucia del Mela and united to Metropolitan Archdiocese of Messina) |
| 1986.09.30 | Italy | Diocese of Sant’Agata de’ Goti was suppressed (to Diocese of Cerreto Sannita–Telese–Sant’Agata de’ Goti) |
| 1986.09.30 | Italy | Diocese of Sant’Angelo dei Lombardi was promoted as Archdiocese of Sant’Angelo dei Lombardi–Conza–Nusco–Bisaccia (gained territory from the suppressed Archdiocese of Conza, Diocese of Bisaccia and Diocese of Nusco) |
| 1986.09.30 | Italy | Diocese of Sant’Angelo in Vado was suppressed (to Metropolitan Archdiocese of Urbino–Urbania–Sant’Angelo in Vado) |
| 1986.09.30 | Italy | Diocese of Sarno was suppressed (to Diocese of Nocera Inferiore–Sarno) |
| 1986.09.30 | Italy | Diocese of Sarsina was suppressed (to Diocese of Cesena–Sarsina) |
| 1986.09.30 | Italy | Diocese of Sarzana was suppressed (to Diocese of La Spezia–Sarzana–Brugnato) |
| 1986.09.30 | Italy | Diocese of Savona was renamed as Diocese of Savona–Noli (gained territory from the suppressed Diocese of Noli) |
| 1986.09.30 | Italy | Diocese of Segni was suppressed (to Diocese of Velletri–Segni) |
| 1986.09.30 | Italy | Diocese of Sezze was suppressed (to Diocese of Latina–Terracina–Sezze–Priverno) |
| 1986.09.30 | Italy | Metropolitan Archdiocese of Siena was renamed as Metropolitan Archdiocese of Siena–Colle di Val d’Elsa–Montalcino (gained territory from the suppressed Diocese of Colle di Val d’Elsa and Diocese of Montalcino, lost suffragan see Chiusi and gained suffragan see Montepulciano–Chiusi–Pienza) |
| 1986.09.30 | Italy | Diocese of Sora was renamed as Diocese of Sora–Aquino–Pontecorvo (gained territory from the suppressed Diocese of Aquino and Diocese of Pontecorvo) |
| 1986.09.30 | Italy | Archdiocese of Sorrento was renamed as Archdiocese of Sorrento–Castellammare di Stabia (gained territory from the suppressed Diocese of Castellammare di Stabia) |
| 1986.09.30 | Italy | Archdiocese of Spoleto was renamed as Archdiocese of Spoleto–Norcia (gained territory from the suppressed Diocese of Norcia) |
| 1986.09.30 | Italy | Diocese of Squillace was suppressed (to Archdiocese of Catanzaro–Squillace) |
| 1986.09.30 | Italy | Diocese of Sulmona was renamed as Diocese of Sulmona–Valva (gained territory from the suppressed Diocese of Valva) |
| 1986.09.30 | Italy | Diocese of Tarquinia was suppressed (to Diocese of Civitavecchia–Tarquinia) |
| 1986.09.30 | Italy | Diocese of Teano was renamed as Diocese of Teano–Calvi (gained territory from the suppressed Diocese of Calvi) |
| 1986.09.30 | Italy | Diocese of Diano–Teggiano was renamed as Diocese of Teggiano–Policastro (gained territory from the suppressed Diocese of Policastro) |
| 1986.09.30 | Italy | Diocese of Tempio–Ampurias was established (from the suppressed Diocese of Ampurias and Diocese of Civita–Tempio and became suffragan of Sassari) |
| 1986.09.30 | Italy | Diocese of Teramo was renamed as Diocese of Teramo–Atri (gained territory from the suppressed Diocese of Atri) |
| 1986.09.30 | Italy | Diocese of Terlizzi was suppressed (to Diocese of Molfetta–Ruvo–Giovinazzo–Terlizzi) |
| 1986.09.30 | Italy | Diocese of Termoli was renamed as Diocese of Termoli–Larino (gained territory from the suppressed Diocese of Larino) |
| 1986.09.30 | Italy | Diocese of Terni was renamed as Diocese of Terni–Narni–Amelia (gained territory from the suppressed Diocese of Amelia and Diocese of Narni) |
| 1986.09.30 | Italy | Diocese of Terralba was suppressed (to Diocese of Ales–Terralba) |
| 1986.09.30 | Italy | Diocese of Todi was suppressed (to Diocese of Orvieto–Todi) |
| 1986.09.30 | Italy | Diocese of Tolentino was suppressed (to Diocese of Macerata–Tolentino–Recanati–Cingoli–Treia) |
| 1986.09.30 | Italy | Archdiocese of Trani was renamed as Archdiocese of Trani–Barletta–Bisceglie (gained territory from the suppressed Archdiocese of Barletta and Diocese of Bisceglie) |
| 1986.09.30 | Italy | Diocese of Treia was suppressed (to Diocese of Macerata–Tolentino–Recanati–Cingoli–Treia) |
| 1986.09.30 | Italy | Diocese of Troia was suppressed (to Diocese of Lucera–Troia) |
| 1986.09.30 | Italy | Diocese of Tropea was suppressed (to Diocese of Mileto–Nicotera–Tropea) |
| 1986.09.30 | Italy | Diocese of Urbania was suppressed (to Metropolitan Archdiocese of Urbino–Urbania–Sant’Angelo in Vado) |
| 1986.09.30 | Italy | Metropolitan Archdiocese of Urbino was renamed as Metropolitan Archdiocese of Urbino–Urbania–Sant’Angelo in Vado (gained territory from the suppressed Diocese of Sant’Angelo in Vado and Diocese of Urbania, lost suffragan see Cagli and gained suffragan see Fano–Fossombrone–Cagli–Pergola) |
| 1986.09.30 | Italy | Diocese of Vallo di Lucania was renamed as Diocese of Vallo della Lucania |
| 1986.09.30 | Italy | Diocese of Valva was suppressed (to Diocese of Sulmona–Valva) |
| 1986.09.30 | Italy | Diocese of Vasto was suppressed (to Metropolitan Archdiocese of Chieti–Vasto) |
| 1986.09.30 | Italy | Diocese of Velletri was renamed as Diocese of Velletri–Segni (gained territory from the suppressed Diocese of Segni) |
| 1986.09.30 | Italy | Diocese of Venafro was suppressed (to Diocese of Isernia–Venafro) |
| 1986.09.30 | Italy | Diocese of Venosa was suppressed (to Diocese of Melfi–Rapolla–Venosa) |
| 1986.09.30 | Italy | Diocese of Vieste was suppressed (to Archdiocese of Manfredonia–Vieste) |
| 1986.09.30 | Italy | Diocese of Viterbo was renamed as Diocese of Viterbo, Acquapendente, Bagnoregio, Montefiascone, Tuscania e San Martino al Monte Cimino (gained territory from the suppressed Diocese of Acquapendente and Diocese of Bagnoregio) |
| 1986.10.17 |  Tanzania | Diocese of Lindi was established (from the suppressed Diocese of Nachingwea and became suffragan of Dar-es-Salaam) |
| 1986.10.17 | Tanzania | Diocese of Nachingwea was suppressed (to establish Diocese of Lindi and Diocese of Tunduru–Masasi) |
| 1986.10.17 | Tanzania | Diocese of Tunduru–Masasi was established (from the suppressed Diocese of Nachingwea and became suffragan of Dar-es-Salaam) |
| 1986.11.08 | Dominican Republic | Diocese of Baní was established (from Metropolitan Archdiocese of Santo Domingo and became suffragan of Santo Domingo) |
| 1986.11.17 |  Liberia | Diocese of Gbarnga was established (from Metropolitan Archdiocese of Monrovia and became suffragan of Monrovia) |
| 1986.12.12 | USA | Diocese of Tyler was established (from Diocese of Beaumont, Diocese of Dallas and Diocese of Galveston–Houston and became suffragan of San Antonio) |
| 1986.12.16 |  Serbia | Archdiocese of Beograd was promoted as Metropolitan Archdiocese of Beograd (with suffragan sees Subotica and Zrenjanin) |
| 1986.12.16 | Serbia | Apostolic Administration of Jugoslavenska Banat was promoted as Diocese of Zrenjanin (became suffragan of Beograd) |
| 1986.12.22 |  Malaysia | Diocese of Sibu was established (from Metropolitan Archdiocese of Kuching and became suffragan of Kuching) |
| 1986.12.22 | Tanzania | Diocese of Mbinga was established (from Diocese of Songea and became suffragan of Dar-es-Salaam) |
