Burkitt's lymphoma is the commonest childhood malignancy in tropical Africa and the predisposing factors include malaria and infection with the Epstein-Barr virus. Recent studies suggest that the prevalence of this neoplasm is declining in this environment. The present study was undertaken to investigate whether there is a real decrease in the occurrence of Burkitt's lymphoma. We analysed 665 cases of childhood malignancies reported in the Ibadan Cancer Registry between 1991 and 1999. Burkitt's lymphoma and retinoblastoma remained the two commonest specific childhood malignancies, accounting for 19.4% and 17.9% of all childhood cancers, respectively. However, this represents a significant decline in the relative frequency of Burkitt's lymphoma when compared with similar surveys for the periods 1960 to 1972 and 1973 to 1990 when Burkitt's lymphoma accounted for 51.5% and 37.1%, respectively, of all childhood malignancies. In Ibadan, it seems that what appeared to be minor changes might actually be a real decline in the incidence of Burkitt's lymphoma and that it might be partly ascribed to improved living conditions and greater control of malaria.