Discoid lateral meniscus in the knee joint is common. From July 1990 through September 1992, the authors performed arthroscopy on 534 symptomatic knee joints. Seventy-seven knees of 72 patients had discoid lateral meniscus. Of the 77 knees treated, 4 (5.5%) had discoid lateral meniscus associated with anomalous insertion of the anterior horn of the medial meniscus into the anterior cruciate ligament. The discoid lateral meniscus was reshaped in the 4 knees, and followup was done from 12 to 24 months (average, 20 months) after surgery. The results were satisfactory, except for 1 patient who damaged his knee in a traffic accident. The authors concluded that this anatomic variant of the medial meniscus was not related to the patients' symptoms, but that reshaping the discoid lateral meniscus did relieve their symptoms.