Snapping syndrome has rarely been reported in the knee. A snapping knee mainly occurs in the case of a translation of the lateral meniscus or a lateral discoid meniscus. Other causes include biceps femoris tendon, semitendinosus iliotibial band, and popliteus tendon. We recently experienced a case of a snapping knee caused by the semitendinosus tendon passing over the medial tibial condyle as a result of trauma.