The postoperative systemic inflammatory response syndrome that is associated with cardiac surgery and the use of cardiopulmonary bypass may contribute to postoperative organ dysfunction and complications. Two recent multicentre randomised clinical trials evaluated the prophylactic use of high-dose corticosteroids to suppress the postoperative inflammatory response in a total of 12,001 cardiac surgery patients. The studies were negative on their primary endpoint, and showed a blend of benefit and harm on secondary endpoints. For dexamethasone, its overall pulmonary benefit was probably the most marked effect, which was demonstrable at multiple levels. There also appeared to be an age-dependent effect of corticosteroids with younger patients (<65 years) with a lower risk of mortality and older patients (>80 years) with an increased risk of mortality when receiving steroids. The differential effects of corticosteroids on patient outcomes between the different age groups may be based on a decreasing intensity of the systemic inflammatory response with advancing age. Future studies should be designed to identify those individual patients who are more susceptible to developing an excessive inflammatory response, and who may receive benefit from anti-inflammatory treatment. © 2016, Netherlands Society of Intensive Care. All rights reserved.