Tragurium, Ancient Latin name of a city in Dalmatia (coastal Croatia), now called Trogir, was a bishopric until 1829 and a Latin titular bishopric until 1933.
In 1050 Tragurium became the seat of a diocese also known as Traù (in curiate Italian) or Trogir in Slavic local Dalmatian language.
On 1 May 1298 it lost territory to establish the Diocese of Šibenik.
On 30 June 1828, the residential see was abolished by papal bull Locum Beati Petri, a Croation dioceses reshuffle, which divided its territory over the then Roman Catholic Diocese of Split–Makarska and its own above daughter Šibenik.
Since 1933 the bishopric was nominally restored and is on the Catholic Church's list of titular sees.
It has had the following incumbents, all of the lowest (episcopal) rank :