The St. Nikola Abbey is a former monastery[1][2][3] of the Augustinian canons and today's mother house of the German Oratory Sisters in Passau, Lower Bavaria, Germany.

[4] St. Nikola was donated by Altmann, Bishop of Passau, the former Kapellan of the Empress Agnes, around 1070 (30 September 1067 according to the Founding Letter; 3 March 1072 according to the privilege of Pope Alexander II).

Several parishes were also incorporated into the monastery, namely Bavaria, Aidenbach, Alburg, Hartkirchen, Pocking and Mittich, and also in Austria Alkofen, Grieskirchen, Münichreith, Neukirchen, Wimsbach, Roitham at the Traunfall and Pollham.

The four Freihöfe of the monastery in the Habsburg countries were withdrawn by the Lower Austrian state property administration and later sold.

The most important was probably the Nikolaihof in Mautern an der Donau; the former Turmhof in Horn now serves as a town hall, and also the Klosterneuburgger Hof in Klosterneuburg and the Freyhof in Aschach on the Danube.