Leiomyosarcomas of the large intestine are unusual neoplasms, comprising less than 0.1% of all malignancies of the colon and rectum. Six cases of leiomyosarcoma of the anus have been reported. The optimal treatment for this neoplasm is not known. The standard surgical approach is abdominoperineal resection. The authors report the seventh case of this rare neoplasm and outline its treatment using local excision and iridium 192 brachytherapy in an attempt to preserve the anal sphincter. In selected patients, conservative surgery followed by radiation therapy may be an alternative to radical surgery, with the goals of local control of the disease and anal sphincter preservation. However, more experience is needed before this approach could be recommended routinely.