Objectives : This study was performed to evaluate the relationship between C-reactive protein(CRP) and carotid intima-media thickness(carotid IMT) in a population of middle-aged Koreans. Methods : A total of 1,054 men and 1,595 women(aged 40-70 years) from Kanghwa County, Korea, were chosen for the present study between 2006 and 2007. We measured high-sensitivity CRP and other major cardiovascular risk factors including anthropometrics, blood pressure, blood chemistry, and carotid ultrasonography. Health related questionnaires were also completed by each study participant. Carotid IMT value was determined by the maximal IMT at each common carotid artery. The relationship between CRP level and carotid IMT was assessed using multiple linear and logistic regression models after adjustment for age, body mass index, menopause(women), systolic blood pressure, total/HDL cholesterol ratio, triglyceride level, fasting glucose, smoking, and alcohol consumption. Results : Mean carotid IMT values from the lowest to highest quartile of CRP were 0.828, 0.873, 0.898, and 0.926 mm for women(p for trend<0.001), and 0.929, 0.938, 0.949, and 0.979 mm for men(p for trend=0.032), respectively. After adjustment for major cardiovascular risk factors, the relationship between CRP and carotid IMT was significant in women(p for trend=0.017), but not in men(p for trend=0.798). Similarly, adjusted odds ratio of increased IMT, defined as the sex-specific top quartile, for the highest versus lowest CRP quartiles was 1.55(95% CI=1.06-2.26) in women, but only 1.05(95% CI=0.69-1.62) in men. Conclusions : CRP and carotid IMT levels appear to be directly related in women, but not in men.