Diocese of Duvno (Latin: Dioecesis Dumnensis or Dioecesis Dalminiensis) was a Latin Roman Catholic diocese in the area of present Bosnia and Herzegovina.
The diocese was born in the area of the Roman province of Dalmatia with the bishop's seat in Delminium. During the rule of the Roman emperor Valerian, c. 257, saint Venantius of Salona was martyred in Delminium.Pope Gregory I mentioned this diocese in his writings from 591.
At the Church Councils of Split it was mentioned as an old emptied diocese. Pope Clement V restored it in the 14th century and since then it regularly had appointed bishops until 1663 when its territory merged into the Diocese of Makarska. The last bishop, Mihalj Jahnn, the Czech Franciscan, found a devastated land and killed Christians.
On 24 March 1846 the Apostolic Vicariate of Herzegovina was founded by seperating from the Apostolic Vicariate of Bosnia and from the Diocese of Dubrovnik. The Vicariate encompassed area of the former Diocese of Duvno.
At the restoration of regular ecclesiastical hierarchy in Bosnia and Herzegovina in 1881, Duvno was located within the boundaries of the Mostar diocese, so the bishop of Mostar adopted the title of Bishop of Duvno, becoming the bishop of Mostar-Duvno to maintain the memory of Duvno Diocese.
Coordinates: 43°43′18″N 17°13′32″E / 43.721696°N 17.225683°E