An account is given of 12 high ruptures of the triceps surae, a traumatic lesion of the medial belly of the gastrocnemius, caused by sudden overstreching of the muscle by concomitant ankle dorsiflexion and full knee extension. In all cases the authors found characteristic clinical features. Surgical exploration in 5 of 12 cases verified the ruptures of the musculotendinous junction of the medial gastrocnemius belly. A follow-up study of 2 years showed that the surgical treatment seems to be better, especially in younger and athletic patients.