Eighteen patients with autologous patellar tendon transplant for reconstruction of the anterior cruciate ligament were examined postoperatively. The time between operation and MR study was up to 3 weeks in ten patients, between 3 and 35 weeks in three patients and more than 35 weeks in five patients. In all patients, Gd-DTPA enhancement on the surface of the ligamentous transplant was visualized. This enhancement was between 1 and 10 mm thick. In all patients, complete stability of the knee joint was achieved, postoperatively. In 15 patients flexion and extension were normal at the postoperative investigation. Three patients had a limitation of knee movement. In these MR studies, significant hyperplasia of the synovial membrane of the entire joint was diagnosed, explaining the persisting problems. Gd-DTPA-enhanced MR of the knee joint allows non-invasive documentation of remodelling following a patellar ligament transplant and possible complications.