The Diocese of Koper (Latin: Dioecesis Iustinopolitana; Slovene: Škofija Koper; Italian: Diocesi di Capodistria) is a Latin diocese of the Catholic Church in southwestern Slovenia. It is part of the ecclesiastical province of Ljubljana. Its cathedral is dedicated to the Assumption of Mary and is located in the Adriatic port town of Koper. A co-cathedral, the Co-Cathedral of Christ the Saviour, located in Nova Gorica, gained its status in 2004. The Latin name of the diocese, Dioecesis Iustinopolitana, is because Koper was in the past named Justinopolis in honour of the Byzantine emperor Justinian II.

• 530: founded as Diocese of Capodistria, united to the Diocese of Trieste between 1828 and 1977
• October 17, 1977: Established as Diocese of Koper from the Diocese of Trieste–Koper, Italy

Cathedrals

• • Cathedral of the Assumption of the Blessed Virgin Mary, Koper
  • Co-Cathedral of Christ the Saviour, Nova Gorica

Minor Basilicas

• • Romarska cerkev (bazilika) Marijinega vnebovzetja, Solkan (Sveta Gora)

Bishops of Koper (Roman rite)

• • 1 Janez Jenko (17 October 1977 – 15 April 1987)
    • Metod Pirih, coadjutor bishop (25 March 1985 – 16 April 1987)
  • 2 Metod Pirih (16 April 1987 – 26 May 2012)
    • Jurij Bizjak, auxiliary, titular bishop of Gergis (13 May 2000 – 26 May 2012)
  • 3 Jurij Bizjak (since 26 May 2012)

• Roman Catholicism in Slovenia

• Media related to Roman Catholic Diocese of Koper at Wikimedia Commons
• Official site
• GCatholic.org
• Catholic Hierarchy

45°32′51.52″N 13°43′50.17″E / 45.5476444°N 13.7306028°E / 45.5476444; 13.7306028