Mammary sarcomas are a heterogeneous group of malignant neoplasms that arise from the mammary stroma (Farrokh et al., 2006). Angiosarcomas, one of the most common forms of mammary sarcoma, are developed from the endothelial lining of the blood vessels. Angiosarcoma of the breast is an exceedingly rare disease that may occur as a primary neoplasm or as a complication of radiation therapy after breast conservation. Only about 20% of angiosarcomas are primary sarcomas. The incidence of primary breast angiosarcoma is about 17 new cases per million women. Primary angiosarcoma of the breast is exceedingly rare, and represents around 0.04% of malignant breast neoplasms. Its incidence among breast sarcomas varies from 2.7% to 9.1%. Breast angiosarcoma is more frequent in young women (20 to 50 years) like in our case with no previous cancer history or other known risk factors. We present a case of a 42-year-old woman, with a painful slowly growing mass in her left breast over a period of one year which on investagitating came out to be primary angiosarcoma of breast.