The development of angiosarcoma of the breast is a recognized complication of breast conservation therapy (BCT), but the evolution, prevalence, and outcome have not been accurately established. We sought to evaluate and review the clinicopathologic, prognostic, and treatment attributes of angiosarcoma arising in the irradiated breast after BCT. We conducted a retrospective chart and slide review of 8 patients seen between 1996 and 2004 with a diagnosis of secondary angiosarcoma. All were treated with mastectomy. Clinical and histopathologic findings were studied and previously reported cases were reviewed. Primary surgery-related breast edema and cellulitis was observed in 7 and 5 patients of the 8 patients studied, respectively. Postirradiation breast edema and grade 2/3 fibrosis occurred in 5 and 8 patients, respectively. The mean age of the patients at onset of the breast cancer and angiosarcoma was 65 and 72 years, respectively. The mean latency period between the treatment of the breast cancer and the diagnosis of angiosarcoma was 75 months. The actuarial rate of 2-year survival for patients presented with single (n = 4) compared with multiple (n = 4) skin lesions was 50% and 0%, respectively (P = .0233). The estimated incidence of angiosarcoma after BCT was found to be 0.14 %. BCT-associated angiosarcoma arises after a relatively brief interval, and breast edema-fibrosis can possibly contribute to its development. Special attention should be paid to skin changes occurring after BCT. The extent of skin lesions is predictive of survival. As shown by a review of the literature, angiosarcomas are often resistant to surgery, chemotherapy, and radiotherapy, and targeted therapy against tumor biological properties may be a new approach to angiosarcoma treatment.