Leiomyosarcoma of the rectum is a rare malignant tumor with an incidence of 0.1%, occurring more frequently in men than in women and in the fifth, sixth, and seventh decades of life. Microscopically it has a characteristic appearance of interlaced bundles of spindle cells with abundant mitosis and cellular pleomorphism. The clinical picture is related to the presence of the rectal mass, the more frequent symptoms being constipation, rectal pain, rectal pressure, and bleeding. The rectal digital examination will demonstrate the mass which in most cases can be confirmed by rectosigmoidoscopy. The mucosa will be involved in about 30% to 50% of cases. Roentgenography is of little value because of the location of this tumor in the lower part of the rectum. Biopsy will be diagnostic. Treatment is radical excision of the tumor and, in this location, abdominoperineal resection of the rectum is usually required. Local excision is followed by a high incidence of recurrence. Prognosis is poor. Survival rates vary. Recent reports in the literature indicate survivals after AP resection from six months to 6 1/2 years.