Cell transplantation patients with blood group incompatibility is essential in order to assess the effectiveness of engraftment and prevent late transfusion reaction which may increase the risk of graft rejection. Subject, method: Four patients including one aplastic anemia and three chronic myelogenous leukemia patients, had ABO, Rh, MNS and Duffy blood group incompatibility with their donors. Gelcard technique was used to type ABO blood group, Rh, MNS and Duffy antigens. Results: The first patient: there was transformation of E antigen (Rh system) and Mia antigen (MNS system)
The second patient: there was transformation of ABO system and C, E antigen (Rh system)
The third patient: there was transformation of ABO system and E antigen (Rh system)
The forth patient: there was transformation of ABO system and Fyb antigen (Duffy system). Conclusion: There were transformation of ABO, Rh, Duffy, MNS blood group system in allogeneic transplantation patients with blood group incompatibility, so red cell antigens typing after transplantation should be applied to follow and assess engraftment in such patients.