Since 1981 in the French Pediatric Oncology Society, a multidrug intensive-pulsed chemotherapy was proposed for bad prognosis B-cell lymphomas (stage II ORL, III and IV) and for B acute lymphocytic leukemias (B-ALL). Between 1981 and 1984, the nine-drug regimen was based on high-dose cyclophosphamide, high-dose methotrexate and cytosine arabinoside in continuous infusion (regimen LMB-81). No irradiation was performed. CNS prophylaxis was made by high-dose methotrexate and by intrathecal injections. No debulking surgery was recommended. Since 1984, considering the high rate of continuous remission, some modifications were made for reducing the duration and toxicity of the treatment of most B-cell lymphomas without CNS involvement (regimen LMB-84). For B-cell lymphomas with CNS involvement and B-ALL, an intensive high-dose multidrug combination was proposed (regimen LMB-86). Between 1981 and 1984, 153 children (stage II ORL: 6%, III: 63%, IV: 31%) were treated with the LMB-81 regimen. The overall disease-free survival rate is 69%. No relapse occurred after 12 months. Only two CNS relapses were observed. Among stage IV, a worse prognosis was associated with initial CNS involvement (disease free survival: 19%). On the contrary, bone marrow involvement was not an adverse prognostic factor. With the LMB-84, the overall disease free survival rate is 74%. A noteworthy reduction of toxicity is observed.