Abstract: Objective To study the effect of pharmacological postconditioning of nitroglycerin and diltiazem on ST elevated myocardial infarction（STEMI）. Methods This study was conducted in 310 patients with STEMI undergoing emergency PCI in our center from January of 2003 to December of 2007. The enrolled patients were randomly assigned to receive pharmacological postconditioning of nitroglycerin with diltiazem（152） or receive none of them（158）. Results In pharmacological postconditioning group,the corrected TIMI frame count was lower and myocardial blush grade was higher. ST-segment resolution 12h after PCI,area under the curve of CK-MB 5 days after operation,and ejection fraction of left ventricular pharmacological postconditioning were also much better in pharmacological postconditioning group than in the control group. Death occurred less in the pharmacological postconditioning group than the control group. Conclusion Pharmacological postconditioning of nitroglycerin and diltiazem can improve myocardial micro perfusion and clinical outcomes,and prevent cardiovascular events in patients with STEMI.