External beam radiation therapy alone or in combination with curietherapy is the recommended treatment for anal canal carcinoma in some countries. In others, surgery is the sole accepted treatment. The results for 64 patients treated by external radiotherapy alone show excellent survival for stage T1T2 tumors but results are poor for large tumors (stage T4). The overall 5 year crude survival rate is 46%. The 5-year results are better for stage T1T2 (72%) than for stage T3T4 (35%). The presence of inguinal node involvement at first examination is a very poor prognostic sign. Local recurrences and metastases are infrequent for stage T1T2, but are more common for stage T3 and T4. Complications follow radiotherapy more frequently in those with stage T3 and T4 tumors. The analysis of local recurrences, complications and survival shows that radiation therapy may be sufficient treatment for stage T1 and T2 and for some stage T3 tumors. The importance of anal sphincter involvement and the poor quality of life for patients who are cured but develop complications, shows the need for combined treatment with surgery and perhaps with chemotherapy. For small tumors the results obtained by external radiotherapy alone are comparable with those obtained by external radiotherapy and curietherapy in terms of survival and complications.