Background: In women, postmenopausal oestrogen supplementation increases levels of systemic markers of inflammation, which are important predictors of coronary heart disease (CHD) risk. Whether endogenous sex hormone levels in men are also related to systemic subclinical inflammation is still unknown. Objective: We tested the hypothesis that higher endogenous sex hormones levels within the physiological range may be associated with systemic subclinical inflammation. Methods: Circulating sex hormone and high-sensitivity C-reactive protein (hs-CRP) levels were determined in 400 apparently healthy men aged between 40 and 80 years. We used multivariate linear regression analysis with the various sex hormones as determinant, and natural log hs-CRP as outcome. Results: Higher levels of total as well as bioavailable oestradiol (E2) were associated with increased natural log hs-CRP levels, which remained statistically significant after adjustment for age and cardiovascular risk factors. Natural log hs-CRP was 0.26 mg/l higher [95% confidence interval (CI) -0.02 to 0.54] in the fourth than in the first quartile of total E2; the P-value for linear trend was 0.05. For bioavailable E2, the difference in natural log hs-CRP between the fourth and the first quartile was 0.30 mg/l (95% CI 0.03-0.56; P-value for linear trend 0.04). After adjustment for age and cardiovascular risk factors, physiological levels of total (TT) or bioavailable testosterone or dehydroepiandrosterone sulfate (DHEAS) were not associated with hs-CRP. Conclusion: Endogenous total and bioavailable E2 levels are significantly associated with CRP among middle-aged and elder men.