Background: RUPTURE of pectoralis major MUSCLE is a very rare and often athletic injury. These days in our country this injury occurs more frequently. This could be due to increase in professional participation of amateur people in different types of sport, like body building and weight-lifting (especially bench-pressing) without adequate preparation, training and taking necessary precautions. In this article, we have tried to review several aspects of complex anatomy of pectoralis major MUSCLE, epidemiology, mechanism, clinical presentations, imaging modalities, surgical indications and techniques of its RUPTURE. Complex and especial anatomy of pectoralis major MUSCLE, in its humeral insertion particularly, have a major role of its vulnerability to sudden and eccentric contraction as the main mechanism of RUPTURE. Also, restoration of this complex anatomy seems to be important during surgical repair to have normal function of the MUSCLE again.