Postoperative wound infection is a common and serious complication of surgery. This review will focus on 2 factors known to modulate perioperative immunity: maintenance of perioperative normothermia and provision of supplemental perioperative oxygen. Hypothermia causes numerous adverse outcomes, including morbid myocardial events, increased blood loss and transfusion requirement, postsurgical wound infections, and prolonged hospitalization. Perioperative normothermia should thus be maintained unless therapeutic hypothermia is specifically indicated. Supplemental perioperative oxygen (inspired fraction of 80% instead of 30%) significantly reduces postoperative nausea and vomiting, diminishes the decrease in phagocytosis and bacterial killing usually associated with anesthesia and surgery, and reduces the rate of postoperative wound infection among patients who undergo colon resection. Available data thus suggest that supplemental perioperative oxygen improves surgical outcome with little or no associated risk.