Aim To investigate the significance of C reactive protein(CRP) in predicting the prognosis after percutaneous coronary intervention(PCI) within 6 hours after attack of acute myocardial infarction(AMI). Methods The CRP levels in plasma was detected in 84 AMI patients within 6 hours after attack,and the patients were divided into increased CRP group(CRP concentration >5 mg/L) and normal CRP group(CRP concentration <5 mg/L).All of the cases underwent PCI.The factors of common clinical data,past medical history,pathological changes of coronary artery were compared between the two groups,and the kak-incident occurrences of heart,for example restenosis,re-infarction in the same position,recurrent angina pectoris,heart failure and cardiogenic sudden death were observed by following-up. Results The CRP levels and the peak value in the increased CRP group were significantly higher than those in the normal CRP group,and there were significant difference between two groups(P<0.05). The quantities of coronary artery in the increased CRP group were more than those in the normal CRP group,and the incidence rate of kak-incident of heart in the increased CRP group was 25.9%(7/27),which was higher than 9.3%(5/54)in the normal CRP group(P<0.05). Conclusion The CRP levels within 6 hours after attack of AMI can be taken as one of the indexes to predict the prognosis of PCI.