Introduction: Hematopoietic stem cells (HSCs) are the stem cells that give rise to all the other blood cells through the proces of haematopoiesis. Hematopoietic stem cell transplantation (HSCT) involves the intravenous infusion of autologous or allogeneic stem cells collected from bone marrow, peripheral blood, or umbilical cord blood to re-establish hematopoietic function in patients whose bone marrow or immune system is damaged or defective. This procedure is often performed as part of therapy to eliminate a bone marrow infiltrative process, such as leukemia, or to correct congenital immunodeficiency disorders. Before transplantation it is necessary to determinate HLA genes and antigens of recipients and donors. For successful allo- transplantation it is necessary to have 10 of 10 (HLA-A, -B, -C, -DRB1, -DQB1) allele HLA loci compatibility between recipient and donor. Goal: The aim of this thesis was to explain the role of HLA in transplantation of HSCs but also to describe and explain difference between the methods in use. Materials and methods: The methods used for the determination of antigens and alleles of HLA are: serological method (microlymphocitotoxicity test) and molecular biology methods: PCR-SSP and PCR-SSO. Results and discussion: After the discovery of HLA haematopoietic stem cells transplantation has become choice in treatment for many hemological diseases. The development of methods for gene and antigen HLA determination leads to increased efficacy in transplantation of HSC. Training methods of molecular biology bring new insights into the even greater complexities of the HLA. Key words: haematopoietic stem cell transplantation, HLA, related and unrelated donors, microlymphocitotoxicity test, PCR-SSP, PCR-SSO.