Purpose : To evaluate the differential features of complete and partial-thickness tears of the posteriorcruciate ligament(PCL) and to describe associated knee injuries at magnetic resonance imaging(MRI). Materials andmethods : Twenty-four subjects were studied,including 15 with complete PCL tears and 9 with partial PCL tears. ThePCL status was determined at arthroscopy in all cases. Knee MRI were perfomed at 1.0 Tesla using a dedicated kneesurface coil. Two radiologists retrospectively reviewed MR images and correlated MRI findings to results ofarthroscopy. Results : There was no statistically significant difference between complete tears and partial tearswith regard to thickness, margination, and signal intensity of the PCL. However, complete tears were more likelyto show focal areas of ligamentous discontinuity (13/15:3/9,p=0.0073). Associated knee injuries were seen in22(92%) patients and were seen more frequently in patients with complete PCL tears, which were bonyinjuries(n=16,67%), tears of the medial collateral ligament(n=12,50%) and menisci(n=11,46%), and stage III jointeffusion(n=17,71%). Conclusion : The most useful MRI criteria for distinguishing complete from partial PCL tear isfocal area of ligamentous discontinuity, that is, complete tears are more likely to show focal areas ofdiscontinuity, whereas partial tears are more likely to show at least some intact fibers.