ABSTRACT: Background:To determine the safely and effectively of del Nido cardioplegia (DNC) in surgery for aortic root disease, with mild hypothermic cardiopulmonary bypass (CPB). Methods:From July to December 2017, all patients undergoing the surgery for aortic root disease (total aortic root replacement, valve-sparing aortic root replacement and replacement of aortic valve plus ascending aorta), with mild hypothermic CPB, were retrospectively reviewed at our institution. Patients were divided into two groups based on the type of cardioplegia: the classical blood cardioplegia (CBC group) and del Nido cardioplegia (DNC group). Demographics, operative details, perioperative data and postoperative complications were recorded and compared. A propensity score matching was performed in this study. Results:The preoperative data in DNC group were similar to CBC group. The volume of ultrafiltration was lower in DNC than CBC group (2,053.49±806.62 DNC vs. 2,666.00±967.14 CBC, P=0.001), when matched. The use of temporary pacemaker was more in DNC group (n=20, 46.5%, P=0.023), and the rate of automatic heart resuscitating was higher in the CBC group (92.0% vs. 72.1% DNC group, P=0.024, unmatched).There were no differences in in-hospital mortality, troponin T (mean 0.66 ng/mL for CBC group vs. 0.49 ng/mL for DNC group, P=0.152), left ventricular ejection fraction (mean 58.37% for CBC group vs. 60.07% for DNC group, P=0.395) or other postoperative complications between two groups, after matching. In subgroup analysis, the ultrafiltration volume was lower in DNC than CBC group (1,932.26±749.39 DNC vs. 2,640.00±996.24 CBC, P=0.004), when ACC time less than or equal to 90 minutes. The apache score was better in DNC group (4.75±3.41, P=0.041), when ACC time greater than 90 min. There were no statistical significances in other characteristics between groups. Conclusions:DNC is safe and effective for surgery for aortic root disease, not inferior to the CBC.