Sialic acid (SA), a family of acetylated derivatives of neuraminic acid, is elevated in patients with coronary heart disease. Cardiac troponin T (cTnT), myoglobin (Mb), and creatine kinase-MB (CK-MB) are specific markers of myocardial injury and are, at present, widely used to detect perioperative myocardial damage during coronary artery bypass grafting (CABG) surgery. The present study investigated the net myocardial release of SA and the cardiac markers (cTnT, Mb, CK-MB) during reperfusion after hypothermic cardioplegic cardiac arrest in 25 patients undergoing elective CABG. Additional paired arterial, central venous, and coronary sinus blood samples were obtained after atrial cannulation before aortic cross-clamping (preischemic sample) and at 1 and 10 min after aortic declamping (reperfusion samples). There were no increase in the SA, cTnT, Mb and CK-MB concentrations before aortic cross-clamping, but there was considerable release of these markers within 10 min after aortic declamping: cTnT release was significantly higher compared with baseline values before aortic cross-clamping. In contrast to SA, Mb, and CK-MB, the difference between baseline and release values for cTnT at 1 min after aortic declamping was not significant. The rate of increase for SA was significantly higher than for Mb, CK-MB and cTnT. SA is a unique and novel marker that could be particularly useful in assessing myocardial cell damage in patients undergoing cardiac surgery.