This study was performed to evaluate the survival and late morbidity rates of a widely used combined chemotherapy and radiation therapy regimen given to patients with carcinoma of the anal canal. One hundred six patients received radiation therapy (5000 cGy given by two anteroposterior-posteroanterior [AP-PA] opposed fields) and chemotherapy (mitomycin C plus 5-fluorouracil [5-FU]) from 1983 to 1989. Patients with primary tumors (n = 86) had a complete response rate of 84% and a 5-year survival rate of 72%. There was no significant difference in survival rate according to tumor stage. Patients with local recurrence (n = 20) after primary surgery had a complete response rate of 50% and a 5-year survival rate of 40%. Fifteen percent of the patients experienced late treatment-related symptoms including anal incontinence, intestinal obstruction, and chronic pelvic pain. The current treatment regimen is effective but carries a considerable risk of complications. As survival rate was independent of tumor stage, the locoregional treatment should probably be less extensive for small tumors than for advanced tumors. This strategy may reduce the late side effects for patients with small tumors without reducing the survival rate.