There are many reports about the snapping syndrome in the hip, shoulder, and ankle, but the snapping knee has rarely been reported. In general, the symptom of this disorder is relatively tolerable and seldom requires operative treatment. We experienced one case of the snapping knee, for which the pain, easy fatigability, and feeling of instability on both knee joints were the main complaints. During an exploratory operation, we confirmed the gracilis and semitendinosus tendon passing over the medial tibial condyle. The clinical, radiologic, and operative findings are reviewed.