Abstract： Objective To examine the expression of circulating microRNA-92a(miR-92a)in patients with ST-segment elevation myocardial infarction(STEMI),and the impact of percutaneous coronary intervention(PCI)on such expression.Methods The level of circulating miR-92a was measured in three groups of patients:58 STEMI patients received PCI,24 STEMI patients received no PCI,and 116 patients with stable angina pectoris(SAP)without PCI.Results On the day next to admission,STEMI patients received no PCI were found to have higher level of circulating miR-92a as compared to SAP patients without PCI(0.286 9±0.816 7 vs.-0.055 5±0.985 5,F=2.438,P=0.121).Twenty-four hours after the PCI,the level of circulating miR-92a in STEMI patients received the procedure was lower than those without it (-0.032 4±0.956 3 vs.0.286 9±0.816 7,F=2.054,P=0.156).The SAP patients(without PCI)had higher survival rate as compared to the STEMI patients without PCI(100.0％ vs.75.0％ P=0.001),and the survival rate in STEMI patients received PCI was higher than those without it(89.7％ vs.75.0％,P=0.088).Conclusions In STEMI patients,the expression of circulating miR-92a is up-regulated.PCI therapy may suppress such up-regulation.Survival rate is higher in patients showing down-regulation of miR-92a.Our data suggest that miR-92a might have potential for diagnosis and therapeutic application in the prevention and treatment of STEMI.