The aim of this study was to determine whether accumulated short bouts of exercise can achieve the same cardiovascular benefits as a single long bout of exercise in sedentary male Japanese workers and to compare the programs’ relative effects on oxidative stress. Twenty-three sedentary male workers were randomly assigned into 2 different exercise programs: a Long-bout group, which performed a single period of continuous exercise (Long-bout group: 30 min × 1) 3 d per week, and a Short-bouts group, which performed 3 short bouts of exercise (Short-bouts group: 10 min × 3) 3 d per week. Cardiovascular risk factors, including the plasma thiobarbituric acid-reactive substances (TBARS) level, were examined at baseline and after both 10 and 20 wk. In the Long-bout group, waist circumference and maximum oxygen uptake (VO_2max) significantly improved after 20 wk. The Short-bouts group demonstrated significant increases in VO_2max after 10 weeks and in HDL-C after 20 wk. Plasma TBARS significantly decreased after 20 weeks in the Long-bout group and tended to decrease (but not significantly) in the Short-bouts group. These results indicate that accumulated short bouts of exercise are an effective option, especially for busy workers, for incorporating exercise into one’s lifestyle.