University of Frankfurt may refer to two (or three) German universities:

• the Johann Wolfgang Goethe University Frankfurt am Main ("Johann Wolfgang Goethe-Universität Frankfurt am Main") in Frankfurt am Main
• the European University Viadrina Frankfurt (Oder) ("Europa-Universität Viadrina Frankfurt (Oder)") in Frankfurt (Oder), or its historical predecessor which existed in the same city from 1506 until 1811, when it was merged with the University of Breslau.

In general English usage, "University of Frankfurt" usually refers to the first one, the one in Frankfurt am Main.