Although often remaining sub-clinical and resolving promptly, postoperative inflammation and oxidative stress can Smoothened Agonist (SAG) HCl contribute to the development of the systemic inflammatory response syndrome, which is frequently observed after cardiac surgery and may further progress to multiple organ dysfunctions and eventual death of patients. Amongst the various endogenous AOX defence lines, selenium plays a unique role as essential co-factor for different AOX-enzymes that are involved in the detoxification of both ROS and RNOS. We recently demonstrated that patients undergoing cardiac surgery with cardiopulmonary bypass and cardioplegic arrest showed a significant intraoperative decrease in Dalvance circulating selenium levels, which was independently associated with the postoperative development of MOD. The underlying mechanisms for the decrease in selenium levels have not been comprehensively elaborated yet. It is known from other antioxidants that their circulating concentrations are depleted when scavenging reactive oxygen species during/after CPB. Furthermore, selenium might be trans located into the interstitial compartment during inflammation and/or might be adsorbed by an extracorporeal circuit. Although off-pump coronary artery bypass grafting has become increasingly popular in selected patients, the effects of OPCAB-surgery on perioperative circulating selenium levels have not been thoroughly studied yet. Due to the abstinence of cardioplegic arrest and preservation of normothermia, OPCAB-surgery should theoretically be associated with less oxidative stress. In contrast, various studies repeatedly demonstrated for OPCAB-surgery a systemic inflammation that is comparable to on-pump cardiac surgery. Comparing on-pump with OPCAB patients should therefore allow to distinguish the effects of oxidative stress from those of inflammation on circulating selenium levels. Therefore we analysed perioperative selenium levels, the overall inflammatory response and oxidative stress in patients undergoing OPCAB-surgery in comparison to patients that underwent onpump coronary artery bypass cardiac surgery.