BACKGROUND Although the involvement of microRNAs (miRNAs) has been intensively studied in myocardial infarction, there is no report on the regulation of miRNAs by ischemic postconditioning in patients undergoing cardiac surgery. We aim to explore the regulation of miRNAs by ischemic postconditioning in double valve replacement. MATERIALS AND METHODS In this prospective, controlled clinical study, consecutive 30 patients undergoing double valve replacement were enrolled. The patients were randomized into two groups, namely an ischemic postconditioning (IPO) group (n = 15) and a control (CON) group (n = 15). For ethical considerations, samples of right atrial muscle were harvested, respectively, 10 min before cardiopulmonary bypass (pre-CPB) and 5 min after aortic declamping (post-CPB) for analysis of miRNAs, genes and apoptosis. RESULTS Compared with the CON group, miR-1 was downregulated, whereas miR-21 was upregulated, and BCL2 messenger RNA (mRNA) was upregulated, whereas BAX mRNA and programmed cell death 4 mRNA remained unchanged in the IPO group. Likewise, a significant increase in BCL2 protein and a striking decrease in BAX protein were observed in the IPO group when compared with those in the CON group. The IPO group showed a significantly smaller increase of terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling-positive myocytes after CPB than CON group. CONCLUSIONS Ischemic postconditioning could regulate miR-1, miR-21, and downstream effectors and resulted in actual attenuation of apoptosis in patients undergoing valvular heart surgery.