PURPOSE: If PCL injury is not treated properly, it may result in progressive instability and functional disability, ultimately degenerative changes of the knee joint. So, we classified fracture type according to extent of displacement and comminution. We will investigate the result and prognosis of operative treatment, and fracture type, associated injuries, and fixation device affect the result. Finally we will ascertain the effectiveness of MRI. Material and Methods: 15 patients were treated in our hospital during the period september 1995 to july 1998. All of them were male. 14 of the 15 patients were treated operatively and 1 patient conservatively. The follow-up period after operative treatment varied from 9 to 30 months. RESULTS: The roentgenograms showed union in all patients. There was subjective satisfaction in 11 of 15 patients. According to the measurement using objective device(KT-2000), in 12 patients, posterior displacement of tibia was less than 2mm, and in 3 patients, less than 4mm. According to Lysholm and Gillquist scoring scale, 11 patients were excellent, 3 patients were good, and 1 patient was fair. The fracture type and fixation device exerts no effect on the results, while associated injury around the knee joint had significant effect on the results. CONCLUSION: Firstly, In avulsion fracture of PCL from tibial attachment, we were able to obtain satisfactory result by operative treatment using the small curvilinear posterior incision. Secondly, By using MRI, we were able to classify the fracture type more exactly and also find associated soft tissue injuries on the traumatized knee joint. As a result, MRI was quite helpful in determining the treatment and prospection of prognosis. Thirdly, The type of device had no effects on the results, no need of removal of fixation devices. Finally, Fixation was made possible by small curvilinear skin incision.