Background: Cardiovascular morbidity is frequent after non-cardiac surgery and the early recognition of cardiac involvement is an essential tool for clinical risk stratification and management. The aim of this study was to investigate the behavior of traditional and emerging cardiac markers, including NT-prohormone-brain natriuretic peptide (NT-proBNP) and ischemia-modified albumin (IMA), in the perioperative period in patients undergoing major uncomplicated orthopedic surgery.Methods: A total of 37 patients undergoing major orthopedic surgery were longitudinally evaluated for NT-proBNP, IMA, cardiac troponin T (cTnT), creatine kinase isoenzyme MB and myoglobin 3h before surgery and 4 and 72h thereafter.Results: NT-proBNP values were significantly increased at 72h postoperative compared to both 3h preoperative and 4h postoperative (NT-proBNP: 20 vs. 4.5pmol/L, pConclusions: The significant increase observed in NT-proBNP suggests that patients undergoing major uncomplicated orthopedic surgery may develop subclinical cardiac stress, presumably attributable to the considerable infusion of liquids. The clinical significance of this finding deserves further investigation, especially in patients at higher risk of heart failure.Clin Chem Med Lab 2006;44:1340–6.