The axillary pectoral muscle (APM) is an accessory fibromuscular structure of the axillary region. It is related to the brachial plexus, axillary vessels and lymph nodes, and is reported with variable incidence in different population groups. A total of 106 axilla were evaluated corresponding to 53 fresh cadavers. The APM was presented in 5 axillary regions (4.7 %), with three unilateral cases (2.8 %) and one bilateral (0.9 %). The total length of the APM ranged from 81.6-119.7 mm, while its tendinous segment measured 13.3-28.1 mm. Muscular belly thickness was 7.1-52 mm and the tendinous segment measured 6.9-20.1 mm. In all cases, the APM originated from the latissimus dorsi muscle and inserted into the lateral lip of humerus intertubercular sulcus, adjacent to the pectoralis major muscle insertion. The evaluated APMs were innervated by the thoracodorsal nerve. In two cases, the APM muscular belly had an anterior medial trajectory to brachial plexus fibers, while in the remaining samples, long fibrous segments of APM insertion were related to the plexus. The incidence of the APM found in the present study is similar to previous reports carried out in cadavers; it was considerably higher than previous anatomy-surgical reports. The importance of APM relies on its involvement with thoracic outlet syndrome, deep thrombosis of the upper limb and complications in axillary lymphadenectomy.