Posterior cruciate ligament is an intraarticular, static and basic stabilizer of the knee joint. Isolated avulsion fracture of the tibial attachment of the posterior cruciate ligament has been reported very rarely, and faliure to recongnize an avulsion of fragment usually results in a poorly functioning knee. The authors analyzed 9 cases of avulsion fracture of posterior cruciate ligament at tibial attachment, who were treated surgically in our hospital between Jan. 1988 to Dec. 1990. The mean follow up period was 18 months. The purpose of this article to discuss cause of the injuries, degree of comminution of fragments in C-T scan, posterior capsular tearing in preoperative arthrogram, surgical approach and method of fixation of the avulsed fragments and following results were obtained. 1. The most common causes of the injury were traffic accident (8 cases). 2. In 5 cases, significant comminution of fragaments were noticed in C-T scan. 3. Only in one case, tear of the posterior capsule was found in preoperative arthrogram. 4. We could expose the fracture site through small posterior hockey stick incision, and there was not any difficulty to fix the fragment. 5. We performed screw fixation in 7 cases, wire-loop & screw in 1 case and ligament staple in 1 case. 6. The results of the treatment were good in 7 cases, fair in 2 cases by criteria of Hughston et al. In case of isolated avulsion fracture of the tibial attachment, the results were relatively good compare to tearing of posterior cruciate ligament at other site.