Angiosarcoma developing in unusual sites such as the gastrointestinal tract is not uncommonly associated with a known eliciting factor. Thus, among hitherto reported cases of angiosarcoma of the small bowel, five were radiation-associated. One additional example of ileal angiosarcoma induced by therapeutic irradiation of endometrial carcinoma is herein reported as a reminder of this causal association. DNA analyses of the primary growth as well as the metastatic deposits showed at least four aneuploid cell clones indicating genetic instability. This observation corresponds to the consistently poor prognosis of radiation-associated angiosarcoma of the small bowel.