Life-style modification has been recommended by the National Cholesterol Education Program as the first approach to reduce serum lipid values and the risk for coronary heart disease. Presented are data from 4587 adults who attended a 3-week residential, life-style modification program consisting of a high-complex-carbohydrate, high-fiber, low-fat, and low-cholesterol diet combined with daily aerobic exercise, primarily walking. Total cholesterol values were reduced by 23%, from 6.06 to 4.66 mmol/L (234 to 180 mg/dL). Low-density cholesterol (LDL-C) values were also reduced by 23%, from 3.9 to 3.0 mmol/L (151 to 116 mg/dL), with most of the change occurring during the first 2 weeks. Male subjects showed a greater reduction in total cholesterol (24.4% vs 20.8%) and LDL-C (25% vs 19.4%) values compared with female subjects. Follow-up studies for 18 months on a small group showed that, in most cases, continued compliance with the program maintained total cholesterol values well below 5.18 mmol/L (200 mg/dL), the level recommended by the National Cholesterol Education Program. High-density cholesterol (HDL-C) was reduced by 16%, but the ratio of total cholesterol to HDL-C was reduced by 11%. Female subjects showed a greater drop in HDL-C values than did male subjects (19.4% vs 11.6%). Serum triglyceride values were reduced by 33%, from 2.29 to 1.54 mmol/L (200 to 135 mg/dL); again, male subjects showed a greater reduction than the did female subjects (37.9% vs 22.5%). Body weight was also significantly reduced, 5.5% for male subjects and 4.4% for female subjects. These results show that most adults can significantly reduce serum lipid values and the risk for atherosclerosis and its clinical sequelae through life-style modification consisting of diet and exercise.