The non-Hodgkin's lymphomas of childhood and adolescence are a heterogeneous group of diseases that constitute 7-10 percent of all pediatric malignancies. Major strides have been made in recent years in understanding the pathogenesis of lymphomas at a molecular level but have not yet led to a modification of clinical management. Between 1973 and 1992, 112 children with B-cell non-Hodgkin's lymphoma were diagnosed. The median age was 5.7 years, with male to female ratio of 3 to 1. Fifty percent presented with abdominal masses, mostly confined to the ileo-ceccal region and to the retroperitoneum. In 39 percent there was head and neck involvement, with 15 percent jaw lesions. Until 1978 patients were treated with the Beilinson Medical Center (BMC) protocol, which yielded only 26 percent disease-free survival for stage IV patients. The introduction of the LMB-86 regimen significantly improved the disease-free survival of patients with advanced stage III and IV disease (84 and 68 percent, respectively). Bone marrow (over 70 percent blasts) and central nervous system involvement remain the major prognostic criteria.