Anatomical variations in the branching pattern of the axillary artery are common and typically include the lateral thoracic, subscapular, and the posterior circumflex humeral (PCHA) arteries. Previous investigations of single specimen dissections demonstrate numerous variations to axillary artery branching, but the frequency of these occurrences is unclear. This study quantifies the frequency of variant branching of the lateral thoracic, subscapular, and posterior circumflex humeral arteries, how it they relate to the posterior cord of the brachial plexus. Axillae of 83 cadavers were dissected to allow examination of the axillary artery and its branches. Data were collected observing the branching pattern of the lateral thoracic, subscapular, and posterior circumflex humeral arteries, as well as those branches spatial relationship to the two terminal branches of the posterior cord of the brachial plexus. Some of the more common variations included the thoracodorsal artery arising from the lateral thoracic artery (LTA) (7.2%) and the subscapular artery (SSA) arising from the LTA (5.4%). The SSA also produced the LTA (4.2%) and the PCHA (12%). The PCHA also originated from the deep brachial artery (8.4%) and traversed the triangular interval to supply the deltoid muscle. These findings are relevant to both the anatomical and clinical fields as provide evidence as to the frequency of variant axillary artery branching and the potential for neurovascular elements to exist in a location other than their classical anatomical description. Clin. Anat. 23:407–412, 2010. © 2010 Wiley-Liss, Inc.