A 26-year-old male with chronic myelogenous leukemia in lymphoid blast crisis received a bone marrow transplant (BMT) from a phenotypically identical, mixed lymphocyte reaction (MLR)-weakly positive unrelated male volunteer donor. The volunteer was obtained from the Tokai Marrow Donor Bank (TMDB), which was established in Japan in 1989. This donor was selected from volunteer donors who were identical with our patient at the HLA-A,B loci, followed by matching at HLA-DQ, DR loci. On MLR testing, the donor's cells showed no response, but the patient's cells showed a low response to the donor's cells (relative response index 0.29). The patient showed rapid hemopoietic engraftment. He developed acute graft-versus-host disease (GVHD) with vesicle formation on palms and soles and mild liver damage, which were successfully treated with intravenous prednisolone 1 mg/kg per day. Although he also suffered from interstitial pneumonitis on day 64 and localized varicella-zoster infection on day 87, and has suffered from moderate stomatitis and dry skin characteristic of chronic GVHD, he is currently 22 months post-transplant with hematological remission and has a normal daily social life.