From 1974 to 1987, 450 children with non-Hodgkins' lymphoma (NHL) were seen at the Institut Gustave Roussy (IGR); 14 children had malignant lymphoma of bone (MLB). Eleven of the 14 were newly diagnosed, whereas three presented in relapse. Nine patients presented with multifocal bone involvement. The median age of these eight girls and six boys was 9.5 years (range 1.25-15 years). Bone pain was present in all patients as the initial symptom. Evaluation included physical examination, routine serum chemistries, complete blood count, chest roentgenography, skeletal survey, radionuclide bone scan, lumbar puncture, bone marrow aspiration, and intravenous pyelography, and/or abdominal ultrasonography. Hypercalcemia was found in six patients. Biopsy was performed in 12 patients, revealing high-grade lymphoblastic lymphomas in all. In two patients diagnosis was made on cytological examination of bone marrow aspirate. Immunophenotyping in four cases, demonstrated non-B, non-T cell origin in three and pre-B cell origin in one. Three patients were treated prior to 1982 with Cyclophosphamide/Oncovin/Prednisone/ADriamycin (COPAD) and seven patients, seen after 1982, were treated with a modified LSA2L2 protocol (LMT). None of the previously untreated patients received radiotherapy. All patients treated with COPAD have died, whereas four out of seven treated with LMT are alive with a median follow up of 51 months (range 36-82 months). One child treated on a pilot study died. One of the three children seen at relapse is disease-free with a follow-up of 98 months after high-dose chemotherapy followed by autologous bone marrow transplantation (ABMT). Five out of six patients presenting with hypercalcemia have died. Results with LMT are encouraging and together with published results suggest that sufficiently intensive chemotherapy can result in complete remission and cure in MLB. Radiotherapy does not seem to be necessary, avoiding possible serious long-term effects. Hypercalcemia is a bad prognostic feature.