Since 1990, the surveillance of childhood cancers in France has been carried out by the National Registry of Malignant Hematological Diseases in Children (RNHE) and, since 2000, by the National Registry of Solid Tumors in Children (RNTSE). Between 2000 and 2004, these registries recorded 8,473 new cases of cancer among children under 15 residing in metropolitan France. The quality of the data is attested by the high average number of sources per case (2.7) and by histological or cytological confirmation of 94% of diagnoses. The age-standardized annual incidence is 156.6 cases per million, with a male-to-female sex ratio of 1.2. Thus, in France, one in every 440 children will develop cancer before the age of 15. The most common cancers are leukemias (29%), central nervous system tumors (23%), lymphomas (12%), and neuroblastomas (8%). Incidence rates are similar to those in other industrialized countries but slightly higher than those previously observed by regional pediatric registries. Although a genuine increase in the incidence of certain types of cancer cannot be formally ruled out, the most likely explanation is an improvement in registration methodology, or even an improvement in diagnostic techniques, particularly for brain tumors. (R.A.)