One hundred and fifty-five consecutive previously untreated adult patients with supradiaphragmatic pathologic stage IA (71) and IIA (84) Hodgkin's disease treated only with radiotherapy (RT) at the Istituto Nazionale Tumori of Milano from 1970 to 1978 were reviewed. Staging procedures included lymphangiography and laparotomy in all cases. Most patients were irradiated with a conventional cobalt machine. Mantle fields were adopted for 36.8% of cases, mainly at stage I, whereas 63.2% received mantle plus paraaortal irradiation. Doses were above 40 Gy for involved sites and 35-40 Gy for prophylactically irradiated nodes. Minimum and median follow-up were 30 months and 6 years, respectively. All patients achieved complete remission at the end of RT. As of June 1981, 89 of 155 patients (57.5%) were alive and free from progression, 60.6% at stage I, and 54.8% at stage II. Relapses occurred in 54 of 155 cases (35%) after a median free interval of 21 months. Marginal recurrences accounted for 5.8%, true recurrences for 9%, nodal extensions for 8.4%, and extranodal extensions for 11.6%. Males older than 40 years and mediastinal involvement were correlated with higher relapse rates. Salvage treatment consisted of RT alone in 8 patients and chemotherapy plus or minus RT in 44, whereas 2 patients died before a new treatment could start. As of June 1981, 38 of 54 relapsed patients (70.4%) were alive and disease free, whereas 2 were alive with evidence of disease. Actuarial overall survival at 6 years was 90.3% for all cases, 97.1% for stage I, and 84.8% for stage II. Treatment toxicity was analyzed, and problems concerning surgical staging procedures, optimal RT and role of chemotherapy as primary or salvage treatment were discussed.