Abstract: Objective To explore if postconditioning may protect the human heart during coronary angioplasty treating acute myocardial infarction.Methods A total of 140 patients undergoing coronary angioplasty for acute myocardial infarction were randomly assigned into postconditionong group and control group.The patients in postconditioning group were performed within 1 minute of reflow by 4 episodes of 1-minute inflation and 1-minute deflation of the angioplasty balloon.The creatine kinase peaks were measured and thormbolysis in myocardial infarction (TIMI) flow and blush grade were analyzed for all patients after the procedure.Ejection fraction was measured in one and six months after the procedure by echocardiography.Results The creatine kinase peak was significantly lower than tha in control group[ (1634 ±522)U/L vs (2476 ±619) U/L,P <0.05].TIMI flow and blush grade were significantly higher than those in control group [ 5.7% (4/70) vs 20.0% ( 14/70),P < 0.05 ].In 1 and 6 months ejection fraction was improved greatly in the postconditioning group compared with control group [ (54.0 ±14.0)% vs (50.0±9.0)%,(56.0±12.0)% vs (52.0±11.0)%,P<0.05)].Conclusion Postconditioning improves the infarcted related artery flow and blood flow in the cardiac tissue,reduces infarct size reduction and improves functional recovery.