From June 1976 to December 1984, 48 previously untreated children with non-Hodgkin's lymphoma (NHL) were treated according to the LSA2-L2 protocol, modified by inclusion of cranial irradiation for patients in stage III and stage IV disease. According to the staging system proposed by Wollner, 4 patients were in stage I, 8 in stage II, 11 in stage III, 8 in stage IVA (less than or equal to 25% blasts in the bone marrow), 15 in stage IVB (greater than 25% blasts in the bone marrow), and 2 in stage IV central nervous system disease. The complete remission rate was 95.8%. The relapse-free survival (RFS) rate of 46 complete responders was 76% after a median observation time of 47+ months. Only 1 of 35 high-risk responder patients developed CNS relapse after prophylactic treatment. Clinical stages were related to the RFS: 100% in stage I-II vs. 69% in stage III-IV. All 8 patients in stage IV were alive without evidence of disease with a median observation time of 59+ months. Fifteen patients in stage IVB who had leukemia-lymphoma syndrome attained 59% RFS with a median observation time of 39+ months. After a median observation time of 38+ months, 29 of 37 patients are off therapy. The results emphasize the value of both the histologic and immunologic features and the stage of disease in predicting the outcome of NHL in children. The LSA2-L2 regimen appears to be a very effective protocol for children with lymphoblastic lymphoma, although it may be less efficacious for patients with large bone marrow involvement.