Variations of circulating C-reactive protein (CRP) levels are supposed to reflect chronic inflammatory process of the cardiovascular system. In particular, it has been reported that high-sensitivity CRP (hsCRP) is a promising marker of coronary heart disease. In the present study, we assessed the relationship between hsCRP and classic cardiovascular risk factors, such as age, blood pressure, smoking habit and serum lipids. Plasma hsCRP was measured by ELISA in 908 subjects, aged 30-79 years, who entered our health-check program. Plasma hsCRP level was 0.54+/-0.02 mg/l in 566 subjects without any disease currently treated. The level was significantly higher in patients treated for hypertension (0.74+/-0.06 mg/l, P=0.002), diabetes mellitus (0.77+/-0.09 mg/l, P=0.016) or coronary artery disease (0.99+/-0.16 mg/l, P=0.008) than in subjects without diseases. In a simple regression analyses of the 566 subjects without diseases, plasma hsCRP positively correlated with male gender, smoking, body mass index, systolic blood pressure, white blood cell count, blood hemoglobin, fasting blood glucose, serum gamma-GTP, uric acid and triglycerides, and inversely correlated with serum albumin and HDL-cholesterol. In multiple regression analysis, white blood cell count (r=0.276, P<0.001), body mass index (r=0.246, P<0.001), age (r=0.122, P=0.001) and smoking (r=0.112, P=0.009) showed independent correlations with plasma hsCRP. It is suggested that variation of circulating hsCRP, even within normal range, is involved in the interrelation of cardiovascular risk factors, such as age, smoking, obesity, high blood pressure and dyslipidemia, which are supposed to promote atherosclerosis and ultimately provoke cardiovascular diseases, such as coronary artery disease.