Squamous-cell carcinoma of the anal canal should be differentiated from anal margin carcinoma because of differences in the recommended treatment and prognosis. Traditional treatment of squamous-cell carcinoma by abdominoperineal resection produces 5-year survival rates in the 50 per cent range. Radical radiation has shown to be effective for the control of local disease, but treatment complications have been cause for concern. Reported 5-year survival rates have ranged from 40 to 80 per cent. Treatment with a combination of radiation and chemotherapy results in a response rate of about 90 per cent and a projected 5-year survival rate of 83 per cent. Strong proponents exist for the combination chemoradiation, whereas others favor radical radiation therapy. Only a prospective clinical trial will determine the treatment of choice. What has evolved in the controversy is that abdominoperineal resection should be reserved for residual or recurrent disease or for the complications of radiation therapy.