Background—CRP, has been known emerging recognized marker of the potential risk of myocardial infarction and stroke. Several studies have reported an increased incidence of cardiovascular events during the winter months. So we investigated seasonal variation of CRP measured by means of a high-sensitivity immunoradiometric assay in apparently healthy Koreans. Methods— The study included 14171 apparently healthy Koreans. (8398 men and 5773 women, 46.0짹11.2 years of age). Anthropometric indices of adiposity, metabolic variables, BP and several cardiovascular risk factors were measured . The high sensitivity CRP was measured by Immunonephelometry Results— The mean(SD) CRP level in this population was 1.06(1.54)mg/L. Mean(SD) CRP lenel in spring, summer, fall and winter were 1.03(1.45) mg/L, 0.97(1.39) mg/L, 1.13(1.64) mg/L and 1.10(1.62) mg/L, respectively. After adjustment for age, sex, fasting blood sugar, low density lipoprotein-cholesterol, body mass index, waist-hip ratio, high density lipoprotein-cholesterol, the odds ratios of elevated CRP of the spring, fall and winter season were 0.986(95% CI, 0.906-1.347 p=0.326), 1.292(95% CI, 1.067-1.563 p=0.009) and 1.306(95% CI, 1.081-1.578 p=0.006), respectively, as compared to the summer seasons. Conclusions— The results indicate a highly significant seasonal variation in CRP, with higher values during the winter and fall as compared to the summer. The elevated plasma CRP level appear to be related to their increased risk in cardiovascular events, which are more prominent during the winter months.