Background No-reflow phenomenon during percutaneous coronary intervention (PCI) for acute myocardial infarction (AMI) is a predictive factor of continuous myocardial ischemia, ventricular remodeling and cardiac dysfunction, which is closely associated with a worse prognosis. This study aimed to evaluate intracoronary nitroprusside in the prevention of the no-reflow phenomenon in AMI.Methods Ninety-two consecutive patients with AMI, who underwent primary PCI within 12 hours of onset, were randomly assigned to 2 groups: intracoronary administration of nitroprusside (group A, n=46), intracoronary administration of nitroglycerin (group B, n=46). The angiographic results were observed. The real-time myocardial contrast echocardiography (RT-MCE), including contrast score index (CSI), wall motion score index (WMSI), transmural contrast defect length (CDL) and serious WM abnormal length (WML) were recorded at 24 hours and 1 week post-PCI.High sensitivity C-reactive protein (Hs-CRP) was examined by immune rate nephelometry. N-terminal prohormone brain natriu retic peptide (NT-proBNP) was tested with enzyme-linked immunosorbent assay. Patients were followed up for six months. Major adverse cardiac events (MACE) were recorded.Results The incidence of final TIMI-3 flow in group A was much higher than that in Group B (P <0.05), final corrected TIMI frame count (cTFC) in group A decreased significantly than that in group B (P <0.01). The CSI, CDL/LV length,WMSI and WL/LV length in group A were significantly lower than that in group B (P <0.01). Levels of Hs-CRP and NT-proBNP at 1 week post-PCI decreased significantly in group A than that in group B (P<0.01). Patients were followed up for 6 months and the incidence of MACE in group A was significantly lower than that in group B (P<0.05).Conclusion Intracoronary nitroprusside can improve myocardial microcirculation, leading to the decrease of the incidence of no-reflow phenomenon and better prognosis.