Cloacogenic carcinoma of the anal canal occurred in 30 patients, comprising 2.4% of all anorectal neoplasms seen in our hospital, and being four times less frequent than squamous carcinoma of the same site. It occurred more often in women than men (ratio 2.3:1); however, its course was more aggressive in men. Most often the tumor arose on the anterior wall of the anal canal, involving the posterior vaginal wall in one third of the women. Liver metastases eventually developed in one third of the 30 patients, and groin metastases in more than one half. Radical surgical excision is the treatment of choice for the primary lesion and groin metastases. Of the 30 patients, 13 have been free from disease for four to 17 years after treatment; the other 17 developed recurrent, metastatic, or progressive disease.