From 1964-1975 43 children with non-Hodgkin's lymphoma (NHL) were treated. 60% of the patients had far advanced disease at diagnosis. Therapy before 1970 consisted of low dose irradiation to the primary and single agent chemotherapy; no C.N.S. irradiation to prevent meningeal recurrence was given. Median survival in this group was 5 months; all patients died. Since 1970 all children with NHL were entered into a modified leukaemia protocol regardless of stage or primary site. Therapy comprised an aggressive multiple drug combination, high dose local irradiation and prophylactic C.N.S. irradiation with intrathecal methotrexate. 41% of the patients treated since 1970 survive in continuous complete remission with a median observation time of 31+ (1-93+) months. All relapses occurred within 30 months after diagnosis. Stage of disease was the most important prognostic factor in our patients. Risk of a primary C.N.S. relapse in the total group was 30% for patients without prophylactic C.N.S. therapy compared to only 6% for patients with treatment.