The Diocese of Treviso is Latin Church ecclesiastical territory or diocese of the Catholic Church in the Veneto, Italy. It is a suffragan diocese in the ecclesiastical province of the metropolitan Patriarchate of Venice.

The Patriarchate of Venice, also sometimes called the Archdiocese of Venice, is a Latin Church ecclesiastical territory or patriarchal archdiocese of the Catholic Church in Venice, Italy. In 1451 the Patriarchate of Grado was merged with the Bishopric of Castello and Venice to form the Archdiocese of Venice.