The posterior cruciate ligament, situated near the center of the knee, functions as a basic stabilizer which provides the central axis during normal and abnormal rotation. When the tibial attachment of the posterior cruciate ligament is avulsed, the knee joint becomes unstable. We treated knees in 16 patients with avulsion fracture of the posterior cruciate ligament at the tibial attachment site by means of screw fixation posteriorly (10 cases) or anteriorly (6 cases) after anatomical reduction through the posterior approach from February 1986 to January 1992. The results were as follows: 1. The traffic accident (dash-board injury) was the most common cause of injury in 11 knees. 2. According to Apleys criteria, the postoperative results of posterior screw fixation group were excellent in 4, good in 4, and fair in 2 knees. In contrast, the results of anterior screw fixation group were excellent in 4 knees, and good and fair in 1 each knee. 3. When there is large fragmentary avulsion fracture of the tibial attachment of posterior cruciate ligament, anterior screw fixation is effective for firm fixation, rendering screw removal easier under local anesthesia. 4. When there is relative smaller avulsed fragment, posterior screw fixation is preferred to anterior screw fixation.