Forty-eight patients with anal canal cancers were treated with surgery and irradiation or irradiation alone during the period 1970-1982. All cases were treated by external megavoltage equipment. The overall 5-year survival was 50%, and the local recurrence rate 33%. According to the therapy, four major groups were analysed: radical surgery followed by post-operative irradiation (5-year survival 43%, local recurrence rate 38%), incomplete major surgery and post-operative irradiation with very inferior prognosis (none of the patients surviving beyond 52 months). Two groups of patients had sphincter-saving procedures: local surgery followed by irradiation (5-year survival 78%, local recurrence rate 22%) and primary irradiation (5-year survival 57%, local recurrence rate 14%). Lymph node positive patients showed a median survival of 24.5 months against 52 months in N0 cases (5-year survival 21% against 50%). Side-effects of radiotherapy were transient and mild, and no late severe sequelae were seen. The data indicate that post-operative external radiotherapy seems insufficient and unable to decrease the local recurrence rate, especially when surgery is incomplete. Both spincter-saving surgery and radiotherapy, as well as primary irradiation, are effective treatment modalities. These data are analysed and future aspects considering combined radiochemotherapy are discussed.