Of about 150 cases reported in the literature on pectoralis major ruptures, 108 were selected as presenting enough data to be analyzed for cause, rupture site, injury mechanism, and treatment outcome. We added data on four of our own cases reported here. All patients yet reported have been men. Rupture of the PM occurs most commonly in sports during weight training, weight lifting, or wrestling when the arm is externally rotated and abducted. Most reported ruptures are complete and are located at the insertion to the humerus. Work-related injuries occur more often at the musculo-tendinous junction. The prognosis is related neither to the age of the patient nor to the location of the rupture. Surgical treatment, preferably within the first 8 weeks after the injury, has a significantly better outcome than conservative treatment or delayed repair.