BackgroundThe axillary vein is an important blood vessel that participates in drainage of the upper limb. Some individuals present a second axillary vein (accessory axillary vein), which is an important collateral drainage path.ObjectivesThe goal of this study was to determine the incidence of the accessory axillary vein and to describe this vessel’s topography.MethodsIn this study, axillary dissections were carried out on twenty-four (24) human cadavers of both sexes that had been fixed with 10% formaldehyde. The upper limbs of the cadavers were still attached to the bodies and the axillary structures were preserved. Data collection was carried out and the axillary structures of the cadavers were compared.ResultsThe incidence of accessory axillary veins was 58.3%, with no significant preference for sex or for side of the body. The accessory axillary vein originated from the lateral brachial vein in 39.28% of cases, from the common brachial vein in 35.71% of cases, and from the deep brachial vein in 25% of cases.ConclusionsIts high incidence and clinical relevance make the accessory axillary vein important for provision of collateral circulation in the event of traumatic injury to the axillary vein.