Traumatic dislocation of the peroneal tendons over the lateral malleolus, caused by sudden, forceful dorsiflexion of the foot accompanied by a powerful contraction of the peroneal muscles, is uncommon but not rare. Main pathologic lesion is rupture of the superior peroneal retinaculum. Operation for acute traumatic dislocation of the peroneal tendons has been a controversial matter, but in chronic recurrent cases, surgical reconstruction is imperative. Authors experienced a patient of acute traumatic dislocation of the peroneal tendons, in whom medial ends of torn retinaculum was inverted into the posterior peroneal groove, and have performed simple repair of ruptured retinaculum, and obtained good result.