Background: Despite increased risk for coronary artery disease and acute myocardial infarction (AMI), prior studies have found that smokers with AMI have lower mortality rates than nonsmokers, a phenomenon often termed ���smoker���s paradox���. The present study was designed to evaluate the etiology of ���smoker���s paradox��� in Korea. Methods: The subjects included 1810 consecutive AMI patients who were admitted and were recruited in KAMIR between Oct. 2005 – Jun. 2007. Of the 1810 subjects, 905 (50%) were smokers , 258(14.3%) were ex-smoker , and 647(35.7%) were non-smoker. Results: Although there is no difference in hospital survival rate among groups, the cardiac mortality rates during one year were significantly higher in the non-smoking group than the smoking and ex-smoker group(16.8% vs 13.4% vs 11.2% , P = 0.049, respectively). There were significantly more male patients and younger patients in the smoking group(P<0.001). But there were longer from onset to arrival time, more hypertensive and DM patients in the non-smoking group(P<0.001). The value of high sensitivity C-reactive protein (hs-CRP) , NT-ProBNP, and casual glucose on admission were significantly higher in the non-smoking group than ex-smoking and smoking group (hs-CRP;17 짹 79 vs 8짹38 vs 8짹41 mg/L, P = 0.026, NT-ProBNP ;2219짹5646 vs 893짹1533 vs 866짹2882 pg/mL, P <0.001, casual glucose; 184짹75.57 vs 173.92짹79.1 vs 171.55짹74.7mg/dL, p=0.005, respectively). After multivariate anaylsis, age was identified as independent risk factors of 1 year mortality, however, smoking was not identified as an risk factor. Conclusion: The reason why non-smokers with AMI have higher mortality rates than smokers ,the so-called ���smoker���s paradox���, is believed to be because non-smoker groups have many conventional cardiovascular risk factors , higher myocardial damage and much more inflammation.