Backgrounds: Physical inactivity and obesity have been directly associated with elevated inflammatory markers involving in atherosclerosis, coronary artery disease, and Type II diabetes. The purpose of this study was to survey the effect of 12-week aerobic training on serum levels of interleukin-18 (IL-18) and high-sensitivity C-reactive protein (hsCRP) in sedentary obese men. Methods & Materials: In this clinical trial study, 20 sedentary obese men were randomly placed at two groups: aerobic training (n=10, age: 27.8±3.2 y, body fat percentage: 31.7±3.4, BMI: 32.0±3.5 kg/m2) and control (n=11, age: 26.7±2.6 y, body fat percentage 31.4±3.2, BMI: 32.3±2.8 kg/m2). For all subjects, height, weight, body mass index, body fat percentage, maximal oxygen consumption, serum levels of IL-18, and hsCRP (after 12 h fasting) were assessed prior to and after training. Aerobic training was accomplished for 12 weeks (3 sessions per week, intensity 60%-70% of the reserved heart rate, duration of each session 20-40 min). Data were analyzed by SPSS-16 by performing two-way ANOVA with repeated measures test. Statistical significance was accepted at P<0.05.Results: Twelve weeks aerobic training decreased serum levels of IL-18 and hsCRP in sedentary obese men, while no significant changes were observed in the control group.Conclusion It appears that aerobic training can, via influencing on parameters IL-18 and hsCRP, play an important role in reducing incidence of atherosclerosis, coronary artery disease, and Type II diabetics in sedentary obese men.