['C-reactive protein (CRP) has been well recognized as a strong independent predictor of short-term and long-term mortality after non-ST-segment elevation acute coronary syndromes. However, limited studies have been conducted correlating CRP levels within 6 h following the onset of ST-segment elevation (ST-se) acute myocardial infarction (AMI) to mortality. The purpose of this study was to evaluate the predictive value of CRP measured by high-sensitivity CRP assay (hsCRP) on 30-day clinical outcomes in patients with ST-se AMI of onset < 6 h undergoing primary percutaneous coronary intervention (PCI).', 'We conducted a prospective cohort study in 146 consecutive patients with ST-se AMI of onset < 6 h who were undergoing primary PCI. Blood samples for hsCRP were obtained in the catheterization laboratory before coronary angiography. Patients were classified into high (group 1: hsCRP > 2.37 mg/L, n = 73) and low (group 2: hsCRP </= 2.37 mg/L, n = 73) hsCRP groups according to the median value of hsCRP after AMI. Univariate analysis demonstrated that the 30-day composite major adverse cardiac events (MACE) [death, recurrent ischemia, and re-occlusion] were significantly higher in group 1 than in group 2 (23.3% vs 4.1%, p = 0.0008). Multiple stepwise logistic regression analysis demonstrated that high hsCRP (p = 0.001), cardiogenic shock (p = 0.0003), and low left ventricular ejection fraction (p = 0.032) were independent predictors of 30-day MACE.'] Is level of high-sensitivity C-reactive protein predictive of 30-day outcomes in patients with acute myocardial infarction undergoing primary coronary intervention?