Aim To investigate the predictive value of red blood cell distribution width (RDW) for major adverse cardiac events (MACE) in patients with acute ST segment elevation myocardial infarction (STEMI) after percutaneous coronary intervention (PCI). Methods 243 clinical cases with acute STEMI after PCI was retrospectively studied. The incidence of MACE in all patients during hospitalization were carefully recorded. The predictive value of RDW for the incidence of MACE in patients with acute STEMI after PCI was analyzed by the receiver operating characteristic(ROC) curve of RDW levels. All the patients were divided into the high RDW group and the low RDW group according to the best cut-off point we determined. The differences of baseline data, laboratory data, coronary angiography, echocardiographic tissue Doppler imaging and the incidence of MACE were compared between the two groups. Results ROC curve showed that the area under the working characteristic curve of subjects with MACE predicted by RDW was 0.634 (95%CI:0.543～0.725,P＜0.05). When the optimal cut-off point of RDW levels was 13.35%, the sensitivity of predicting MACE was 52.5%, the specificity was 68%. The rate of MACE in the high RDW group(RDW≥13.35%) was higher than in the low RDW group(RDW＜13.35%)(24.42% vs 12.10%, P＜0.05). The multivariate Logistic regression analysis showed that the high RDW levels may be associated with MACE in acute STEMI patients after PCI treatment during hospitalization(OR=3.7,5%CI:1.275～7.093,P＜0.05). Conclusion RDW may be an independent risk factor for MACE in STEMI patients after PCI during hospitalization.