Objective: Angiographic slow/no-reflow during emergency percutaneous coronary intervention (PCI) in patients with ST-elevated acute myocardial infarction (AMI) may result in unfavorable outcomes. The aim of our study was to investigate the clinical factors and angiographic findings that predict slow/no-reflow phenomenon and the long-term prognosis of AMI patients with angiographic slow/no-reflow. Methods: A total of 210 consecutive AMI patients, who underwent primary PCI within 12 hours of symptom onset were divided into a normal flow group (thrombolysis in myocardial infarction [TIMI] flow grade 3, n = 169) and a slow/no-reflow group (<= TIMI flow grade 2, n = 41), based on cineangiograms performed during PCI. Results: A total of 41 patients (19.5%) developed slow/no-reflow phenomenon. Univariate analysis showed that delayed reperfusion, high thrombus burden on baseline angiography, and acute hyperglycemia all correlated with slow/no-reflow (P < 0.05 for all). Multivariate analysis revealed that hyperglycemia on admission (= 10 mmol/L; odds ratio [OR]: 1.7, 95% confidence interval [CI]: 1.423-2.971, P = 0.012), reperfusion time (= 6 h; OR: 1.4, 95% CI: 1.193-1.695, P = 0.040), and high thrombus burden (OR: 1.6, 95% CI: 1.026-2.825, P = 0.031) were significant and independent predictors of angiographic slow/no-reflow. The 6-month mortality and incidence of major adverse cardiac and cerebrovascular events (MACCE) were significantly higher in the slow/no-reflow group than in the normal flow group. Angiographic slow/no-reflow was independently predictive of MACCE (hazard ratio [HR]: 2.642, 95% CI: 1.304-5.932, P = 0.028). Conclusion: Delayed reperfusion, high thrombus burden on baseline angiography, and blood glucose level on admission can be used to stratify AMI patients into a lower or higher risk for angiographic slow/no-reflow during PCI. In addition, angiographic slow/no-reflow predicts an adverse outcome in AMI patients.