The introduction of more sensitive techniques, such as LuminexA (R) for HLA antibody screening of patients awaiting organ transplantation has resulted in a better understanding of transplantation immunology and improvements in clinical practice. The interpretation of the results obtained only by LuminexA (R) can lead to inaccurate evaluation of a patient's antibody status and unjustified rejection of a potential organ donor. The aim of this study was to demonstrate the benefits of performing HLA antibody screening in the sera of patients on the waiting list for organ transplantation by two different assays, complement dependent cytotoxicity (CDC) and LuminexA (R). A retrospective analysis was performed on 563 pretransplant serum samples from 141 patients on the kidney transplantation waiting list in Rijeka, tested from March 2012 until March 2015. All samples were tested in parallel by the CDC assay and the LuminexA (R)-based assay. Out of the 563 samples tested 302 (53.7%) tested negative for HLA antibodies and 88 (15.6%) positive by both assays. From 173 (30.7%) samples with discordant results 149 (26.5%) were CDC negative and LuminexA (R) positive, while 24 (4.3%) were CDC positive and LuminexA (R) negative. Among the Luminex positive patients seven did not experience any immunizing events. Evaluation of the HLA antibody status in patients on a waiting list for organ transplantation should be based on the results of the both CDC and LuminexA (R) (or other sensitive) assays in accordance to information about patient's clinical status and exposure to immunizing events.