We report a bone marrow transplant which was HLA matched, with major and minor ABO and minor RhD incompatibility (anti-RhD antibody) between the donor and recipient. When engraftment occurred, the recipient developed an anti-RhD antibody of donor origin detected by direct and indirect antiglobulin tests (DAT, IAT) and showed signs of mild hemolytic anemia. With the disappearance of the recipient RBCs, the DAT became negative and the hemolysis disappeared, while the anti-RhD alloantibody persisted in the patient's serum. This case emphasizes the importance of close immuno-hematological monitoring in patients undergoing allogeneic BMT with ABO-RhD incompatibility between recipient and donor.