The aim of the present study was to investigate the clinical predictive value of pre-infarction angina (PIA) combined with mean platelet volume to lymphocyte count ratio (MPVLR) for no-reflow phenomenon and shortterm mortality in patients with ST-segment elevation myocardial infarction (STEMI) undergoing percutaneous coronary intervention (PCI). Material/Methods: A total of 1009 STEMI patients who had undergone PCI were enrolled and subdivided into 4 groups based on the occurrence of PIA and the presence of MPVLR above or below the cutoff value. Analysis of the predictors of the no-reflow phenomenon and 90-day mortality was conducted. Further, evaluation and comparison of the clinical predictive value of PIA, MPVLR, and their combination were done. Results: Both MPVLR (odds ratio [OR]=1.476, 95% confidence interval [CI]: 1.401 to 1.756, P<0.001; hazard ratio [HR]=1.430, 95% CI: 1.287 to 1.643, P<0.001) and PIA (OR=0.905, 95% CI: 0.783 to 0.986, P<0.001; HR=0.878, 95% CI: 0.796 to 0.948, P<0.001) were independent predictors of no-reflow phenomenon and 90-day mortality. Spearman's rank correlation test revealed that MPVLR (r=-0.297, P<0.001), monocyte to lymphocyte count ratio (MLR) (r=-0.211, P<0.001) and neutrophil to lymphocyte count ratio (NLR) (r=-0.389, P<0.001) in peripheral blood were significantly negatively correlated with postoperative left ventricular ejection fraction (LVEF). Upon comparing the area under curve (AUC), the MPVLR combined with PIA achieved better performance in differentiating no-reflow phenomenon (AUC=0.847, 95% CI: 0.821 to 0.874) and 90-day mortality (AUC=0.790, 95% CI: 0.725 to 0.855), than the GRACE score, MPVLR and PIA alone, and had similar performance to all other pairwise combinations of the GRACE score, MPVLR and PIA. Conclusions: High MPVLR and PIA were independent predictors of the no-reflow phenomenon and 90-day mortality in patients with STEMI after PCI. Moreover, Combined application of MPVLR and PIA can effectively predict the occurrence of the no-reflow phenomenon and 90-day mortality.