Aim To investigate the effect of alprostadil in the acute myocardial infarction （AMI） patients treated by delayed PCI with the ^99mTc- methodxy isobutyl isomitrile （^99mTc-MIBI） gated-myocardial perfusion stable image （G-MPI）.Methods 60 patients were enrolled. Patients had the first myocardial infarction beyond 12 hours without thrombolytic therapy. Patients were divided into control group （n30） and alprostadil group （n30） randomizedly. The control group were given conventional treatment and delayed PCI, while alprostadil group were treated by conventional treatment, delayed PCI and alprostadil. In all patients, G-MPI was received in the first week and the twelfth week after AMI. Then left ventricular end diastolic volume （LVEDV）, left ventricular end systolic volume （LVESV）, left ventricular ejection fraction （LVEF） and ischemic area （IA） were compared. Results LVEDV, LVESV, LVEF and IA between the two groups had no significant differences in the first week. After 12 weeks, LVEDV and LVESV of alprostadil group were significantly lower than those of control group, but LVEF of alprostadil group was significantly higher than that of control group. IA of alprostadil group was significantly less than that of control group. Conclusion The effects of alprostadil and delayed PCI include complete revascularization, improvements in perfusion, faster restoration of ventricular function.