Five patients with multiple cancers that included hematologic malignancies are described. The incidence of multiple cancers in hematologic malignancies has been 8.8% in the past two and a half years at our hospital. The combinations were: 1) primary bilateral breast cancers and acute monocytic leukemia; 2) breast cancer, malignant lymphoma and gastric cancer; 3) malignant lymphoma and gastric cancer; 4) malignant lymphoma and prostate cancer, and 5) colon cancer and multiple myeloma. Our experience suggests an increasing incidence of multiple cancer in hematologic malignancies.