We describe an HLA matched bone marrow transplantation with minor ABO incompatibility and RhD mismatch (donor RhD negative and recipient RhD positive). GVHD appeared on day +96 and therapy with steroid and cyclosporin was started. When GVHD disappeared and immunosuppressive therapy was stopped (2 years after BMT), an anti-RhD antibody was detected in the patient's serum. The delayed appearance of this antibody may have been associated with the prolonged immunosuppression that was required for treatment of the patient's GVHD.