Abstract: AIM: To evaluate the effect of super-selective intracoronary injection of nitroprusside on no-reflow phenomenon of primary percutaneous coronary intervention (PCI). METHODS: Forty-three acute myocardial infarction (AMI) patients with no-reflow phenomenon after primary PCI were included in the study. Super-selective intracoronary infarction related artery (IRA) injection from ZEEK thrombus aspiration catheters was used in 21 cases, and routine injection from guiding catheter was used in the other 22 cases. Nitroprusside was injected (100 μg) by 2-sec bolus in both groups. Coronary arteriography (CAG) was rechecked 10 min after injection, and TIMI as well as CTFC of IRA blood flow were evaluated. RESULTS: No-reflow phenomenon was markedly relieved in both groups. All cases in the super-selective group restored TIMI III blood flow and CTFCs of IRA decreased from 83.7±7.02 to 26.5±5.81 (P<0.001) after super-selective intracoronary injection of nitroprusside, whereas those in the routine group decreased from 84.5±6.45 to 33.8±11.9, with significant difference in IRA TIMI and CTFC between groups (P<0.01). CONCLUSION: Super-selective injection of 100 μg nitroprusside in IRA effectively improved no-reflow phenomenon in primary PCI of AMI.