Since human leucocyte compatibility has a crucial effect in renal transplantations and there is the need for full-match HLA compatibility between the donor and the recipient for successful bone marrow transplantations. It is clearly evident that HLA system plays a major role in kidney and hone marrow transplantations. Hence, accurate and reliable identification of these antigens is very important. We perform CDC assay for the typing of HLA-A,-B in our EFT accredited laboratories. In case of homozygosity or detection of an ambigious antigen, molecular methods are performed in addition to CDC. The purpose of our study was to demonstrate the comparative results of two methods concerning the cases in which molecular typing was needed in addition to CDC and to list the antigens that could not he identified by CDC hut molecular typing. The study group included 1567 individuals consisting of patients with chronic renal deficiencies (n=646), hematological malignancies (n=646) and their donors (n=275). Samples were typed by CDC and PCR-SSP/SSO methods for HLA-A,-B. The study group was divided into 5 groups as cases with single HLA-A and/or-B and with ambigious HLA-A and/or-B. By molecular methods, 2138 tests were performed. The concordance between CDC assay and molecular methods was 8.8% for HLA-A and 14.2% for HLA-B. The most frequent antigens which could not be identified by CDC but molecular methods were HLA-A32, B15 (7.3, 15.8 %). We believe that performing molecular tissue typing methods at least particularly to patient samples will increase the transplantation success.