Computer-assisted surgery (CAS) has not been a routine part of cranio-maxillofacial surgery so far. Out of a total pool of experience with 102 navigation-guided procedures between 1/1998 and 12/2000, we report on 2 cases of navigation-aided resection of severe ankylosis of the mandibular condyle with a predetermined safety margin of the resection towards the middle cranial fossa, and identification of the oval foramen. We regard navigation-aided resection of an ankylosis of the mandibular condyle as a valuable additional technique in this potentially complicated procedure. Keywords: Intraoperative Navigation, computergestützte Chirurgie