Carcinosarcoma of the breast is an extremely rare and aggressive tumour with two distinct cell lines comprising epithelial and mesenchymal components, with few cases reported in the literature. The prognosis of carcinosarcoma breast is less favourable compared to more common types of breast cancers such as infiltrating ductal or lobular carcinomas. These tumours form a diagnostic and therapeutic challenge. A case of carcinosarcoma breast in a 36 years old woman is presented here.