Results of an EORTC trial (20751) in non-Hodgkin lymphomas are presented. Patients were treated in the same way independent of the histological type. There were 468 patients in the study of whom 124 patients were in stage I (85% 5 year survival), 57 in stage II (55%), 121 in stage III (55%) and 166 in stage IV (45%). Using the Kiel classification the low grade lymphomas were subdivided into two categories: those with a follicular (80% 5 year survival) and with a diffuse cell pattern (50% 5 year survival) with an intermediate prognosis compared with the high grade lymphomas (35% 5 year survival). Treatment was stratified according to stage. In stage I regional radiotherapy was given followed by randomization for maintenance chemotherapy with Vincristine, Cyclophosphamide and Prednisone. No influence in survival was seen (85% at 5 years), although disease free survival was better in the maintenance chemotherapy group (75% vs 55% at 5 years). In stage II regional radiotherapy was followed, after randomization, by transdiaphragmatic irradiation, all patients received maintenance chemotherapy. The group was too small to draw conclusions about the effect of this treatment. Primary radiotherapy in stage II disease with diffuse histology gave bad results. Patients in stage III and IV were treated with 8 courses of chemotherapy with Adriamycin, VM26, Cyclophosphamide and Prednisone, given in two different time schedules. Iceberg radiation was then given to areas with initially large or slowly responding disease. All patients had maintenance chemotherapy. No difference was found for the 2 chemotherapy schedules in remission rate, disease free interval and survival. In stage III and IV patients with a follicular lymphoma have a longer relapse free interval and total survival (39% and 68% at 5 years) compared with those with a lymphoma diffuse histology (19 and 30% at 5 years). Patients with stage IV disease due to bone marrow involvement only had a better prognosis compared with stage IV disease for other reasons.