A case of radiation-associated angiosarcoma of ileum and concurrent adenocarcinoma of colon developed almost simultaneously about 13 years after radiotherapy for her cervical carcinoma was reported. She had received an operation for hepatic flexure colon cancer and was found to have ischemic changes of both terminal ileum and right side colon but no evidence of other abnormality in abdominal cavity. Four months later, she experienced an episode of acute abdomen and subsequent emergent exploratory laparotomy disclosed perforation of ileum. The pathological examination proved the lesion to be a wide spreading angiosarcoma of ileum, which was considered to be radiation-related.