Computed tomography (CT) of the knee was performed in 160 patients following double-contrast arthrography. Seventy-five synovial folds on the medial wall of the knee joint were found, and 63 of these plicae could be considered mediopatellar plicae. In 10 of the 63 cases, long, thick mediopatellar plicae were found, which could lead to a mechanical internal derangement. Twelve synovial folds did not conform to the classic description of a mediopatellar plica. These folds probably represent synovial tissue reaction, since they were most commonly seen in patients who had undergone meniscectomy.