Primary angiosarcomas arising from the alimentary tract are rare and only a few cases have been reported in the literature. We report a case of an angiosarcoma of the sigmoid colon with intraperitoneal bleeding but not rectal bleeding. A 21-year-old female patient received a laparotomy and a mass lesion over the sigmoid colon was found with active bleeding. A sigmoid colectomy was performed as a curative resection. Grossly, the sigmoid colon contained a kidney shaped, hemorrhagic tumour from the submucosal layer extension to the antimesenteric side. Intraluminally, the mucosa of the colon was intact. Microscopic examination revealed a high grade angiosarcoma composed of fascicles of spindle cells and solid sheets of epithelioid cells. Immunohistochemical stains revealed a positive result for CD31 and the endothelial nature of the malignancy was confirmed. Smooth muscle antigens, desmins, cytokeratins AE1/AE3 and CD117 were all negative. The patient is still alive without evidence of recurrence or metastasis at a three-year follow-up appointment. Owing to the availability of immunohistochemical studies, some atypical sarcomas would now be correctly classified as angiosarcomas. Since no optimal adjuvant treatment is effective, curative surgical excision is still the best choice of treatment.