Rupture of the pectoralis major muscle is a rare clinical entity. Only few reports have discussed its MRI or CT features. We have reviewed the imaging features of four cases of complete rupture of the pectoralis major muscle. One case of acute injury underwent surgical repair. MRI is useful in delineating the site and extent of the rupture in relation to the musculotendinous junction, which will help the surgeons with possible treatment options and surgical planning. Because of the complex anatomy of the pectoralis major muscle near its insertion on the humerus and the signal characteristics of hematoma and edema in the muscle, axial T2-weighted images were most valuable for the evaluation of acute and subacute injuries. Axial T1-weighted images were helpful in delineating chronic injuries. CT is inferior to MRI for direct visualization of muscle rupture.