Since 1872, 168 rectal leiomyomas were reported in the world literature. Their incidence is very low, one leiomyoma for every 2000 or more rectal tumors. Those leiomyomas located in the anal canal and sphincter are the rarest. A case is reported that appears to be the 11th in such a location. The incidence of these lesions is highest between the ages of 40 and 59 yr. Most patients have a combination of symptoms rather than a single one, the most frequent of these being the presence of a mass, bleeding and constipation. Almost always, the chain of events that leads to the diagnosis starts when the tumor is discovered by digital examination of the rectum. The lack of reliable criteria of malignancy and the marked tendency to recur shown by these tumors are the 2 main problems in selecting the operative procedure. Those tumors with an original size of 5 cm or more in largest diameter are the ones that showed the highest tendency to recur, mostly as sarcomas. These lesions should be treated radically from the beginning, especially when they recur. More adequate follow-up studies are needed.