Purpose This study was designed to examine the effects of 8 weeks of circuit exercise training on blood lipids, insulin resistance, cardiovascular function, and metabolic syndrome risk factors in 40~50s male bus drivers. Methods Twenty-nine bus drivers were randomly assigned to one of two groups, i.e., circuit exercise training group (TR: n=14) and control group (CON: n=15). Subjects in TR participated in circuit exercise training 30-40 min per session, three sessions per week for 8 weeks, whereas subjects in CON were asked to maintain their normal life pattern for same intervention period. The variables regarding body composition, blood lipids, insulin resistance, cardiovascular function, and number of metabolic syndrome risk factors were measured and compared between two groups as well as between pre- and post-test. Data were analyzed using repeated two-way ANOVA with post hoc test. Results Main results of the present study were as follows: 1) Waist circumference, waist-hip ratio, body mass index, and percent body fat decreased significantly in TR. 2) LDL-C decreased and HDL-C increased significantly in TR. 3) Fasting plasma insulin and HOMA-IR decreased significantly in TR. 4) Regarding cardiovascular function, diastolic blood pressure and mean arterial pressure decreased significantly in both TR and CON. hs-CRP were not changed significantly; however, it tended to be decreased TR. 5) Number of metabolic syndrome risk factors decreased significantly in TR(2.86±0.86 to 1.50±0.76). Conclusions It was concluded that 8 weeks of circuit exercise training would be beneficial for improvement of blood lipid profiles and insulin resistance, resulting in preventing metabolic syndrome. In particular, it would be very clinically meaningful that number of metabolic syndrome risk factors decreased from 2.86±0.86 to 1.50±0.76 by the circuit exercise training.