To determine which anthropometric, biochemical, and cardiovascular variables are associated with serum levels of C-reactive protein (CRP) in young, apparently healthy men, a cross-sectional study of 179 male college students aged 18 to 22 years was performed. Multiple regression analysis was used to derive models for serum CRP concentrations in terms of the other variables measured. Although CRP was positively correlated with body mass index (BMI), percent fat mass, and serum leptin, correlations with BMI (r = 0.15, P =.05) and percent body fat (r = 0.16, P =.003) were not as strong as the correlation with leptin (r = 0.28, P =.0002). CRP was also associated with resting heart rate (r = 0.14, P =.05), heart-rate corrected QT (QTc) interval (r = 0.22, P =.003) and several components of the insulin resistance (IR) syndrome. CRP showed a strong and negative association with high-density lipoprotein (HDL)-cholesterol (r = -0.26, P =.0005) and a marginal and positive association with triglyceride (r = 0.14, P =.05). Although CRP was associated with fasting insulin (r = 0.15, P =.04), it was not related to serum adiponectin or IR index estimated using homeostasis model assessment (HOMA). Multiple regression analysis indicated that serum CRP was positively related to serum leptin (P =.003) and QTc interval (P =.01), and negatively correlated with HDL-cholesterol (P =.01, R(2) = 0.15). In young, apparently healthy men, serum leptin but not BMI was independently associated with serum CRP, suggesting that amount of body fat may be the most significant predictor of CRP. Although low-grade inflammation was associated with long QTc interval and low HDL-cholesterol, the mechanism underlying these associations is an important question to be addressed.