From January 1980 to December 1987, 100 patients with carcinoma of the hypopharynx, staged according to TNM (UICC-1978) criteria, received exclusive radiation therapy at the Radiotherapy Department of the General Hospital of Varese. The median follow-up is 9 months (range: 1-97). Irradiation was delivered with 60Co or with 10 MV photons and tissue-equivalent bolus. Two opposed parallel lateral fields or rotational technique were used, with progressive shrinking of treated volume in order to spare the spinal cord after 45 Gy. Direct fields of electron beams (6-15 MeV) were employed as boosts on the residual nodes. Median total doses: 64.5 Gy to T and N1-3, 45 Gy to N0. A conventional fractionation (2 Gy once a day, 5 times a week) was used in 37 outpatients, while an accelerated hyperfractionated regimen (1.5 Gy twice a day, 5 times a week, with a six hours' interval between each fraction) was employed in 63 inpatients, in order to shorten hospitalization. The five-year overall survival (Kaplan-Meier) of the 100 treated patients is 10%, while the five-year disease-free survival of the 40 patients in complete clinical remission at the end of radiation therapy is 19.8%. The five-year loco-regional control rate after exclusive radiotherapy is 19.1%. Complete remission at the end of treatment seems to represent the only significant prognostic variable affecting survival: five-year overall survival is 32% for the 40 patients achieving complete remission and only 4.4% for the others (p less than 0.05). On the contrary, tumor extension (T class) seems to affect only the two-year local control rate: 35.2% and 10.9% for T1 + T2 and T3 + T4 respectively (p less than 0.1). The main cause of failure after radiation therapy is represented by the lack of control at the primary site (T) alone or associated with regional adenopathies (N). The analysis of isoeffect parameters, according to CRE model, has not shown any evident dose-response relationship for local control. Late effects were observed in 7% of the patients and were similar to those reported in the literature. The occurrence of both distant metastases, 3% in our experience, and secondary tumors (9%) is lower than those previously reported. The present retrospective study strongly reconfirms the inadequacy of exclusive radiation therapy as the sole treatment modality for carcinoma of the hypopharynx and suggests the need of combination therapy (surgery and radiation) as primary treatment.(ABSTRACT TRUNCATED AT 400 WORDS)