1. Eight surgically confirmed ruptures of the pectoralis major are presented in detail. These and three other ruptures observed by our colleagues are added to the total of forty-five published cases.
2. The mechanisms of injury were direct trauma, excessive athletic stress, or attempts to prevent falls. The rupture occurs within the muscle belly, by avulsion of its tendinous insertion or separation of its musculotendinous junction.
3. The results of treatment depend on the portion of the muscle injured. Early surgical repair is recommended for the distal tendinous injuries, conservative therapy for ruptures of the muscle fibers.
4. Rupture of the pectoralis major muscle probably occurs much more frequently than reports would indicate.