A parking lock (1) of a transmission comprises a parking lock wheel (2) that is rotationally fixed relative to a shaft (25) and a locking ring (3) that is rotationally fixed relative to a housing (24), the locking ring (3) can be displaced axially into a positive locked connection with the parking lock wheel (2) by an engaging element (4) and can be released from the locked connection by a hydraulically actuated release element (6).