The clinicopathological features of 14 Japanese patients with Burkitt's lymphoma (seven studied by us and seven reported by others) are reviewed. Five patients were 12 years of age or younger. Six patients presented with abdominal masses and five with jaw tumors. Twelve patients manifested blood and/or marrow involvement at the time of initial diagnosis (four patients) or later in the course of the disease (eight patients). Most of the patients had a rapid clinical course in spite of combination chemotherapy. The malignant cells from all patients exhibited a B-cell phenotype; the surface immunoglobulin was IgM in 13 and IgG in one. Two patients had tumors positive for Epstein-Barr virus-determined nuclear antigen while all the others lacked this antigen in their tumors. Chromosome analysis revealed a standard t(8;14) translocation in nine patients, a 14q+ chromosome without an identifiable donor chromosome in two and variant translocations t(2;8) in two and t(8;22) in one.