The Fifteenth International Symposium of the Foundation for Promotion of Cancer Research entitled 'New Horizons in the Diagnosis and Treatment of Hematological Malignancies Based on Molecular Genetic Features' was held in Tokyo on January 15-17, 2002. Twenty-nine invited speakers, including 12 from abroad and 17 from Japan, presented the updated results of their research. After an overview of the classification of hematological malignancies, new findings on some disease entities based on novel immunophenotypic and molecular genetic features were presented. The results of gene expression profiling and BCL6 and C-MYC gene rearrangement in diffuse large B-cell lymphoma were presented and oncogenic mechanism of acute myeloid leukemia was discussed. In the treatment of non-Hodgkin's lymphoma and acute leukemia, the present consensus and future directions were discussed based on the results of multicenter trials in the USA and Japan. As a molecular targeting therapy, the remarkable effect of a BCR-ABL tyrosine kinase inhibitor, STI571, in chronic myeloid leukemia and gastrointestinal stromal tumor was presented. Thereafter, promising results of active immunotherapy, chimeric anti-CD20 monoclonal antibody, anti-CD20 radioimmunoconjugate and anti-CD22 immunotoxin for B-cell lymphoma were presented. Finally, recent advances in allogeneic hematopoietic stem cell transplantation were discussed, focusing on reduced-intensity preparative regimens. The recent advances in basic and clinical research on hematological malignancies would lead to further improvement in the prognosis and quality of life of patients suffering from leukemia or lymphoma.