Supernumerary breast or polymastia is a congenital malformation of the breast which results in the existence of a supernumerary mammary gland in an ectopic situation, especially axillary. Its diagnosis is easy in the presence of a nipple and a milky discharge, but can be difficult in their absence leading to confusion with other etiologies of axillary mass. Its management is most often surgical because of the aesthetic impact but also to prevent the risk of neoplastic degeneration. We report through this observation a case of an axillary supernumerary breast collected in the service in order to describe the different pathological and therapeutic aspects.