Breast angiosarcoma may occur de novo, or as a complication of radiation therapy, or chronic lymphedema secondary to axillary lymph node dissection for mammary carcinoma. In our effort to characterize the clinicopathologic features of breast angiosarcoma, we reviewed all breast angiosarcoma cases in the University of Kansas Medical Center and Ohio State University Medical Center archives from 1997 to 2007. Clinical histories and follow-up data for identified patients were reviewed. The tumors were graded histologically according to Rosen's method. Only 11 angiosarcomas were identified among more than 5000 malignant breast neoplasms (0.1%-0.2% incidence) for the last 10 years. Eight cases (6 high grade, 1 intermediate grade, 1 low grade) were identified as postradiation angiosarcoma (postradiation time interval, 4-12 years), and 3 cases were identified as primary angiosarcomas (1 high grade, 2 low grade). Follow-up (median, 36 months) revealed that 3 cases of postradiation angiosarcoma recurred as skin and/or chest wall lesions and 1 case of primary angiosarcoma developed liver metastases (all high-grade). In conclusion, breast angiosarcoma remains a rare disease. Rosen's method for grading breast angiosarcoma is easy to implement and correlates well with clinical outcome. There are no distinct clinical or histologic differences between primary and postradiation breast angiosarcomas.