Background/Aim. The EuroSCORE II has recently been developed with an idea to provide better accuracy in prediction of perioperative mortality in the patients who underwent open heart surgery. The aim of this study was to validate clinical performances of the European System for Cardiac Operative Risk Evaluation (EuroSCORE) II risk stratification model in the Serbian adult cardiac surgical population undergoing open heart surgery. Methods. The Euro-SCORE II values on 10,048 consecutive patients undergoing major adult cardiac surgery from 1st January 2012 to 31st March 2017, were prospectively calculated and entered the institutional database. The discriminative power of the model was tested by calculating the area under the receiver operating characteristic curve (AUC). The calibration of the model was assessed by the Hosmer-Lemeshow (H-L) statistics and the observed to expected (O/E) mortality ratio. The patients with the EuroSCORE II values of 0.5-2.50%, > 2.50-6.50%), and > 6.50% were defined to be at low, moderate, and high perioperative risk, respectively. Results. The observed in-hospital mortality was 3.86% (388 of 10,048) and the mean predicted mortality by the Euro-SCORE II was 3.61%. The discriminatory power was very Key words: mortality; predictive value of tests; risk assessment; thoracic surgical procedures. Apstrakt Uvod/Cilj. EuroSCORE II je razvijen nedavno sa idejom da se obezbedi bolja tačnost u predviđanju perioperativnog mortaliteta bolesnika podvrgnutih operacijama na otvorenom srcu. Cilj rada je bio da se provere kliničke performanse modela za stratifikaciju operativnog rizika u kardiohirur-giji-EuroSCORE II (Evropski sistem za procenu kadiohirurškog operativnog rizika) kod odraslih bolesnika u Srbiji kod kojih se izvode kardiohirurške procedure. Metode. Vrednosti EuroSCORE II za 10 048 uzastopno operisanih (od 1. januara 2012. do 31. marta 2017. godine) odraslih kardiohirurških bolesnika prospektivno su izračunate i unete u bazu podataka Instituta za kardiovaskularne bolesti Ključne reči: mortalitet; testovi, prognostička vrednost; rizik, procena; hirurgija, torakalna, procedure.