The French National Registry of Childhood Leukaemia and Lymphoma (NRCL) covers the whole French mainland population aged less than 15 years (approximately 11 million children) for all childhood haematopoietic tumours since 1 January 1990, except Hodgkin's disease, which has been registered since 1 January 1999. During the period from 1990 to 1999, 5757 cases of leukaemia, lymphoma and myelodysplastic syndrome were registered in the NRCL, with an average of 2.5 sources per case. The age-standardized incidence rates per million per year were 43.1 for leukaemia (34.3 for acute lymphoblastic leukaemia, 7.1 for acute myeloblastic leukaemia, 0.6 for chronic myeloid leukaemia and 0.5 for chronic myelomonocytic leukaemia), 8.9 for non-Hodgkin's lymphomas and 6.7 for Hodgkin's disease. Down's syndrome was present in 110 cases of acute leukaemia (2.5%) and three cases of non-Hodgkin's lymphoma (0.3%). The incidence of acute lymphoblastic leukaemia showed a typical peak at age 2 years for girls and 3 years for boys. The incidence rates of leukaemia and non-Hodgkin's lymphoma did not show any temporal trends over the 10 year period.