Sixteen patients affected by epidermoid carcinoma of the anal canal were treated preoperatively by means of an i.v. infusion of mitomycin C (15 mg/m2) on day 1 and 5-fluorouracil (750 mg/m2) days 1 to 5, followed by radiotherapy (3000 R in 3 weeks). Four to 6 weeks after the end of radiotherapy the response to the preoperative treatment was evaluated by means of biopsy. A reduction of the neoplastic mass was observed in 13 of the 16 patients. An evident correlation exists between the stage of the tumor and 1) the response to preoperative treatment, 2) local recurrence, and 3) long-term survival. In fact: 3/4 T1 patients reached a complete response (CR), and 1/4 T1, 5/5 T2 and 4/7 T3 patients achieved a partial response (PR); only 3/7 T3 patients never responded to preoperative treatment. After the initial surgery, only T2 (3/5) and T3 (4/7) patients underwent a second operation for a recurrence. Overall survival at 42 months was 62.5% (T1, 100%; T2, 80%; T3, 28.5%).