Objective: There is experimental evidence that phosphocreatine (PCr) can decrease ischemia/reperfusion injury of the heart. The authors investigated if PCr would improve heart performance as compared with standard treatment in cardiac surgery. Design: Meta-analysis of randomized controlled trials. Setting: Hospitals. Participants: Adult and pediatric patients undergoing cardiac surgery. Interventions: The ability of PCr to improve cardiac outcomes as compared with standard treatment was investigated. Measurements and Main Results: PubMed/Medline, Embase, Scopus, Cochrane Library, China National Knowledge Infrastructure, WANGFANG DATA, and VIP Paper Check System were searched to March 1 2017. The authors included 26 randomized controlled trials comprising 1,948 patients. Random and fixed-effects models were used to estimate odds ratio (OR) and mean difference (MD) with 95% confidence interval (CI). PCr use was associated with reduced rates of intraoperative inotropic support (27% v 44%; OR 0.47, 95% CI 0.35-0.61; p < 0.001), major arrhythmias (16% v 28%; OR 0.44, 95% CI 0.27-0.69; p < 0.001), as well as increased spontaneous recovery of the cardiac rhythm immediately after aortic declamping (50% v 34%; OR 2.45, 95% CI 1.82-3.30; p < 0.001) as compared with standard treatment. The use of PCr decreased myocardial damage and augmented left ventricular ejection fraction in the postoperative period; however, MD for these outcomes were small and do not seem to be clinically significant. Conclusions: In randomized trials, PCr administration was associated with reduced rates of intraoperative inotropic support and major arrhythmias, and increased spontaneous recovery of the cardiac rhythm after aortic declamping. Large multicenter evidence is needed to validate these findings. © 2017 Elsevier Inc.