PURPOSE: Whether skin disinfection of the surgical site using chlorhexidine-alcohol is superior to povidone-iodine-alcohol in reducing reoperation and surgical site infection rates after major cardiac surgery remains unclear. METHODS: CLEAN 2 was a multicenter, open-label, randomized, two-arm, assessor-blind, superiority trial conducted in eight French hospitals. We randomly assigned adult patients undergoing major heart or aortic surgery via sternotomy, with or without saphenous vein or radial artery harvesting, to have all surgical sites disinfected with either 2% chlorhexidine-alcohol or 5% povidone-iodine-alcohol. The primary outcome was any resternotomy by day 90 or any reoperation at the peripheral surgical site by day 30. RESULTS: Of 3242 patients (1621 in the chlorhexidine-alcohol group [median age, 69 years; 1276 (78.7%) men] and 1621 in the povidone-iodine-alcohol group [median age, 69 years; 1247 (76.9%) men], the percentage required reoperation within 90 days was similar (7.7% [125/1621] in the chlorhexidine-alcohol group vs 7.5% [121/1621] in the povidone-iodine-alcohol group; risk difference, 0.25 [95% confidence interval (CI), - 1.58-2.07], P = 0.79). The incidence of surgical site infections at the sternum or peripheral sites was similar (4% [65/1621] in the chlorhexidine-alcohol group vs 3.3% [53/1621] in the povidone-iodine-alcohol group; risk difference, 0.74 [95% CI - 0.55-2.03], P = 0.26). Length of hospital stay, intensive care unit or hospital readmission, mortality and surgical site adverse events were similar between the two groups. CONCLUSION: Among patients requiring sternotomy for major heart or aortic surgery, skin disinfection at the surgical site using chlorhexidine-alcohol was not superior to povidone-iodine-alcohol for reducing reoperation and surgical site infection rates.