The aim of the study is to present current applications of molecular biology methods in immunohematology as well as the status of their implementation in the Polish Blood Transfusion Service. Molecular biology methods are used for: analysis of molecular background of blood cell antigens in individuals with discrepant results of serological tests, identification of RhD antigen with weak expression undetectable by serological methods in blood donors, identification of weak D type antigen in recipients unsusceptible to alloimmunization. These methods are also used for noninvasive study of fetal genes in plasma samples of immunized pregnant women with serological incompatibilities and in RhD negative pregnant women for qualification to antenatal prophylactic administration of anti-D immunoglobulin. Molecular biology is also an important tool for diagnostics of patients with antibodies to high-frequency blood group antigens (HFA) or for patients immunized with HPA and HNA antigens and for identification of “antigen-negative” blood donors for such patients. In Poland, all these tests are available and in use.