BACKGROUND. The role of radiotherapy alone in the sterilization of anal canal epidermoid carcinomas of 5 cm or more remains to be assessed. Thus, the outcomes of patients treated with radiotherapy alone (RT) versus those treated with preoperative radiotherapy and surgery (RS) were compared retrospectively. METHODS. Between 1972 and 1990, 185 patients were treated with curative intent either with RT alone (n = 147) or with RS (n = 38). The Mean tumor length was 6.18 +/- 1.14 cm and was significantly longer in the RS group (6.55 +/- 1.29 cm) than in the RT group (6.08 +/- 1.08 cm) (P = 0.02). The median follow-up was 77 +/- 57 months and 93 +/- 60 months (P = 0.23) for the RT and RS groups, respectively. For the RT group, the first course of radiotherapy was 40 to 45 Gy in the pelvis for 4 to 5 weeks; after a rest of 4 to 6 weeks, radiotherapy was boosted an additional 15 to 20 Gy for 2 weeks. The RS patients received 40 to 45 Gy in the pelvis for 4 to 5 weeks, then received surgery after a median period of 54 days. RESULTS. The overall 10-year cancer specific survival rates were 58% in the RT group and 66% in the RS group (P = 0.48). The T-stage 10-year cancer specific survival rates were 68% in the RT group and 67% in the RS group for T2 tumors (P = 0.96); 57% in the RT group and 53% in the RS group for T3 tumors (P = 0.85); and 42% in the RT group and 40% in the RS group for T4 tumors (P = 0.05). In the RS group, the local control rate was 75% (3/4) for T2 tumors; 74% (17/23) for T3 tumors; and 82% (9/11) for T4 tumors. In the RT group, the local control rate was 77% (34/44) for T2 tumors; 70% (58/82) for T3 tumors; and 60% (12/20) for T4 tumors. In the RT group, the anal conservation rate was 61% (27/44) for T2 tumors, 59% (48/82) for T3 tumors, and 55% (11/20) for T4 tumors. Local tumoral control and a functioning anus were present in 72 out of 147 (49%) patients [52% (23/44) for T2 patients, 52% (43/82) for T3 tumors, and 30% (6/20) for T4 patients]. In the RS group, the grade 3 complication rate was 9% (13/146) and in the RS group, 5% (2/38). CONCLUSION. For patients with T4 tumors, preoperative radiotherapy and surgery seemed to be better in terms of survival and local tumor control rate, but the difference was not significant probably because the number of patients in the RS group was small. For these large tumors, the treatment should probably be more aggressive, combining chemotherapy and radiation therapy, but the increase of local control in relation with the addition of cytotoxic chemotherapy to irradiation is not proved.