Although Burkitt's lymphoma (BL) is classified as one entity in the World Health Organisation (WHO) classification, we wondered whether BL should not be considered as a different disease in children compared with adults. Netherlands Cancer Registry (NCR) data were obtained from 1994 to 1998 (n=203). Detailed clinical data from two treatment protocols were compared: one for adults up to the age of 65 years (n=27) and one for children (n=80). All slides of the two clinical studies were centrally reviewed which included immunophenotyping and when necessary breakpoint analysis of MYC/8q24. Only cases with an unambiguous diagnosis of BL (classical and atypical BL) were accepted. The age distribution of BL-patients showed a bimodal distribution with a peak at the paediatric age and a steady increase after approximately 60 years of age. Most of the patients were males (89% for children and 78% for adults) and only male patients showed this bimodality. Children more often had extranodal disease (81% vs. 59%), whereas adults more often had nodal disease (89% vs. 53%). Based on epidemiology and clinical presentation, the concept that BL is one disease should be re-challenged.