Angiosarcoma of the breast is a very rare conjunctive tumor. It is a primitive malignant proliferation of the endothelial cells of the vascular tissue of the gland. It occurs in both a primary form without a known precursor, and a secondary form that has been associated to a history of irradiated breast tissue. Both forms have a malignant behavior and a poor prognosis. We report a case of breast angiosarcoma diagnosed by histology and treatment consisting of a mastectomy supplemented by chemotherapy and radiotherapy.