Ilmmünster Abbey (Kloster Ilmmünster or Stift Ilmmünster) was formerly a collegiate foundation (Kollegiatstift), and originally a Benedictine monastery, in Ilmmünster in Bavaria in Germany.
The monastery was dedicated to Saints Arsatius, whose relics were here, and Quirinus, whose relics were at Tegernsee Abbey, founded by the same brothers, to which Ilmmünster was affiliated.