Abstract: Leiomyosarcoma of the colon, excluding that of the rectum, is extremely rare. We report a case of leiomyosarcoma of the ascending colon with a brief review of literature. The clinical manifestations in our case were typical: abdominal pain, diarrhea, anorexia, and a palpable tumor that was firm, smooth, and mobile inspite of its bulk. Toxic features, cachexia and weight loss were less prominent. Morphologically the tumor was of dumbbell type with intracolic and extracolic components. The microscopic picture, consisting of spindle-shaped smooth-muscle cells with pleomorphism and one to three mitotic figures per high-power field, was characteristic. In the absence of local spread, a hemicolectomy was considered curative, but our patient developed extensive metastasis in 25 months. The correlation between mitotic activity of the tumor and prognosis in our case was consistent with that reported in literature.