A retrospective analysis of 183 consecutive patients with tonsillar carcinoma observed from 1970 through 1984 and treated by external radiotherapy was carried out. The data were analyzed retrospectively to determine the factors affecting prognosis. Tumor size (T) and lymph node involvement (N) were found to be predominant prognostic factors. The difference in 5 year survival rate between T2 and T3 tumors was significant, and that between N1 and N3 was highly significant, whereas difference in survival could be found between N0 and N1 groups. The primary tumor was controlled by radiotherapy alone in 90% of cases of T1 lesions, 58% of T2, 37% of T3 and 11% of T4, and lymph node metastases was controlled in 70% of N1 cases, 0 of N2 and 15.5% of N3. Twenty-three patients underwent salvage surgery after radiotherapy had failed and the actuarial 5 year survival rate was 75% for stage I, 40% for stage II, 30% for stage III and 13% for stage IV.