We report a case of 33-year-old Japanese female who had B-cell lymphoblastic lymphoma with Burkitt's lymphoma (BL)-like morphologic feature. Both breasts were involved and the resected tissue showed starry sky macrophages and a proliferation of lymphoblasts containing lipid droplets. The nucleus of the lymphoblast was oval or indented. The neoplastic cells examined expressed TdT, CD10, CD14, CD38, and WH14 (a marker of pre-B cell leukemia/lymphomas). Southern blotting analysis showed a rearrangement of the immunoglobulin heavy chain gene and germline configurations of T-cell receptor gene and c-myc 3rd exon gene. The immunophenotype and genotype of this neoplasm were different from those of previously reported BLs, but identical to those of B-cell lymphoblastic lymphoma. This case, therefore, was regarded as B-cell type lymphoblastic lymphoma containing lipid droplets.