The improving effects of a lifestyle education program on the arteriosclerosis index in male volunteers were studied, and the data obtained were analyzed in relation to their lifestyle. Out of the 307 male employees in a company in Nagoya with a slightly high risk of lifestyle-related diseases, 49 volunteers aged 30 to 60 years participated in an intervention program involving brief individual counseling and the distribution of a health-education newsletter once a week for 12 weeks. This program, aimed mainly at reducing the daily energy intake, consisted of (1) reducing the intake of sugar, confectionery and oil, (2) increasing the intake of seaweed, yellow and green vegetables, and soybean and its products, and (3) enhancing physical activity as much as possible, at least more than 7, 000 steps in a day. The results after the intervention trial show that nearly 50% of the volunteers had continued to implement objectives 2 and 3, and almost all had maintained objective 1. While the serum total cholesterol level remained unchanged, the serum HDL-cholesterol level had significantly increased, with significant improvement to the arteriosclerosis index. The improving effects continued for four years after the intervention trial. Those volunteers who could be judged to have a stable and active lifestyle best met objectives 1 and 2, and showed a higher serum HDL level.