- 3 December 1924 (renamed as Apostolic Vicariate of Phát Diêm) - 7 May 1932 (lost territory to establish Apostolic Vicariate of Thanh Hoá) The Diocese of Phát Diệm (Latin: Dioecesis de Phat Diem) is a Roman Catholic diocese of Vietnam.

The creation of the diocese in present form was declared November 24, 1960.

By 2004, the diocese of Phát Diêm had about 144,721 believers (15.9% of the population), 31 priests and 65 parishes.

[7] This cathedral complex was built between 1875 and 1899 and comprises four churches and one basilica, as well as several parks, ponds and grottos.

This article on a Roman Catholic diocese in Vietnam is a stub.