In order to establish an efficient γδ T cell-mediated immunotherapy for hematological malignancies, we attempted to evaluate cytotoxicity against tumor cells by γδ T cells, which were generated from blood cells of patients with myeloma and lymphoma by culturing with zoledronate and a low dose of IL-2. Although γδ T cells were expanded in patients with myeloma and lymphoma as well as normal persons, the amplification rates of γδ T cells before and after culturing varied from patient to patient in myeloma and lymphoma. γδ T cells generated in patients with myeloma and lymphoma showed a potent cytotoxic ability against myeloma/lymphoma cell lines as shown in γδ T cells generated in normal subjects. In addition, γδ T cells generated in a patient with myeloma showed a cytotoxic ability against self myeloma cells freshly prepared from bone marrow. However, the same γδ T cells were demonstrated to be non-cytotoxic to normal cells of the patient. These data demonstrated that γδ T cells, which could be expanded in vitro from blood cells of patients with myeloma and lymphoma by culturing with zoledronate and IL-2, possess a sufficient cytotoxic ability against tumor cells. These findings suggested that in vitro generated patients' γδ T cells could be applied to γδ T cell-mediated immunotherapy for hematological malignancies.