BACKGROUND: There are few studies about association between the metabolic syndrome and smoking status (onset of smoking, duration, number of cigarettes per day, pack-years) in long-term smokers. And CRP level, a risk factor of the metabolic syndrome, is known to be higher in smokers than in non-smokers. This study was done to assess the association of smoking status and CRP level with the metabolic syndrome in long-term smokers. METHODS: Healthy men aged 40 years old or more who visited the Samsung Medical Health Promotion Center were selected. We examined the participants' clinical characteristics by using self-reporting questionnaires, laboratory data, and Bruce treadmill test. We estimated the prevalence of the metabolic syndrome and identified the association between smoking status, CRP, and the metabolic syndrome by multiple logistic regression method. RESULTS: The prevalence of the metabolic syndrome was higher in the long-term smokers (21.4%) than in the non-smokers (17.5%). The odds ratios of developing the metabolic syndrome were 2.46 (95% CI 1.31~4.62) and 2.57 (95% CI 1.20~5.50) in men who smoked 20~29 and 30 or more cigarettes, respectively, compared with those who smoked 1~9 cigarettes. And the odd ratio was 1.41 (95% CI 1.01~1.97) in men who had high CRP level (> or =0.3 mg/dl) compared with the normal CRP group. The number of cigarettes had statistically positive association with the CRP level (coefficient beta=0.059; P<0.05). CONCLUSION: The prevalence of the metabolic syndrome was higher in the long-term smokers than in the non-smokers, and proportional to the number of cigarettes in the long-term smokers. The number of cigarettes smoked per day was correlated positively to the CRP level in the middle-aged Korean men.