Background Increased levels of inflammation markers, such as C-reactive protein (CRP) and tumor necrosis factor-α , have been found in insulin resistance syndrome. Those with elevated levels of high-sensitive CRP (hs-CRP) are at a higher risk for coronary heart disease. In the present study, we evaluated whether maximum oxygen uptake and insulin resistance are related to hs-CRP for the primary prevention of coronary heart disease. Methods and Results The subjects were 50 subjects who did not have diabetes mellitus. A multi-step treadmill exercise test was performed to obtain the maximum oxygen uptake when assessed by computerized breath-by-breath analysis. As an index of insulin resistance, the homeostasis model insulin resistance index (HOMA-R; fasting glucose × fasting insulin/405) was used. In addition, bodyweight, body mass index, subcutaneous fat thickness, total cholesterol, high-density lipoprotein (HDL) cholesterol, and triglyceride were measured. Multivariate analysis revealed that hs-CRP was significantly correlated with HDL-cholesterol, uric acid, γ-glutamyl transpeptidase and maximum oxygen uptake. The maximum oxygen uptake showed the smallest odds ratio was in terms of the relationship with hs-CRP. Conclusions The present study suggests that the development of exercising habits increases the maximum oxygen uptake. Furthermore, an elevated maximum oxygen uptake decreases HOMA-R and reduces the inflammatory marker CRP, suggesting that exercising habit plays an important role in the primary prevention of coronary heart disease. (Circ J 2005; 69: 452 - 457)