Angiosarcoma of the breast is a rare and very aggressive tumors originated from endothelial cells lining blood vessels. We report a case of a 55-year-old postmenopausal female with a primary breast angiosarcoma diagnosed just a one year after radical hysterectomy and radiation therapy due to endometrial cancer. The patient initially presented with postmenopausal bleeding. Cytology and biopsy of the endometrium were performed and endometrial adenosquamous carcinoma was diagnosed followed by radical hysterectomy and postoperative local radiatiotherapy (50 Gy). One year later patient presented with a great painful tumorous mass in the right breast. Physical examination revealed an oval tumor, located in upper and outer quadrant of the right breast, around 15 cm in diameter. Mammography and ultrasonography were performed. The angiosarcoma of the breast was confirmed by biopsy. The patient underwent radical mastectomy. Histopathology proved the diagnosis of angiosarcoma (high-grade, numerous mitoses over 10/10 HPF, necrosis, “blood lakes”, infiltrative borders). Differential diagnosis of a breast angiosarcoma should be considered in all painful breast tumours no mather the time and the location of the previous radiation treatment even if benign characteristics of these masses have been detected by mammography and breast ultrasound.