Prognosis of stage IV Burkitt's lymphoma according to Murphy's classification and FAB L3 acute lymphoblastic leukemia was dramatically improved during the two last decades through a very intensive and short duration chemotherapy. At the end of the seventies the rate of cure was 30% in stage IV Burkitt's lymphoma with up to 25% blasts in the bone marrow, and there was no cure for cases with central nervous system involvement and FAB L3 ALL. The French Society of Paediatric Oncology (SFOP) was one of the international leading groups in treatment research in these diseases. Successive LMB protocols led to the international LMB96 protocol involving France, United Kingdom and United States of America. Currently, event free survival of all stage IV Burkitt's lymphoma and FAB L3 LAL is higher than 85%, and approaches 80% in the cases with central nervous system involvement and 90% in the cases without CNS involvement. Relapse cases, occurring always early, still have a very bad prognosis and remain a challenge for the future.