A case of leiomyosarcoma of is reported. A 78-year-old man was admitted with a history of constipation and deformation of the stools. Barium contrast study and sigmoidoscopy showed a submucosal tumor of the rectum. On computed tomography and angiography, the tumor was suspected of being leiomyosarcoma. Abdominoperineal resection was performed. Microscopic examination revealed a leiomyosarcoma of the rectum and widespread lymph node metastases were found. Leiomyosarcoma of the rectum is an uncommon tumor. In our country, 89 cases have been reported. Six had lymph node metastases initially and another six subsequently. We have referred to the literature on leiomyosarcoma of the rectum.