Thirty consecutive patients with epidermoid carcinomas of the anal canal larger than 2 cm were treated with the concomitant application of radiation and two cycles of chemotherapy (5FU and mitomycin-C) between January 1982 and January 1988. Twenty-eight patients were treated with curative intention and two for palliation only. All patients were reexamined after a period of one to 2 months, under light general anesthesia, and any residual tumor or scar tissue was biopsied. Control biopsy was positive in eight patients. Three of six patients who had abdominoperineal excision died from locoregional recurrence; the remaining are alive and cancer free after 1 to 4 years. Two patients had local excision; one is alive and the other died of other cancer metastasis four years later. Seventeen patients who had negative biopsies are alive and free of disease after 1 to 5 years; two died of unrelated causes, two died with distant metastasis (present prior to treatment), and one died with locoregional recurrence. Locoregional failures occurred in four patients (13.3 percent) in the entire series. Individualization of each patient, adjustment of doses, and carefully executed radiation and chemotherapy are the most important points for the success of treatment.