The clinical manifestations of coronary artery disease exhibit strong age dependence. To investigate this phenomenon, we examined for age-related changes in two groups of offspring of parents with early coronary disease (on or before age 60) - 10 subjects aged 15-25 years and 21 subjects aged 35-45 years. Familial hypercholesterolemia was excluded by history. For each subject, body mass index (BMI) was < 85th percentile for age. Fasting lipoproteins were measured after sequential ultracentrifugation. Triglyceride(TG) was measured hourly following a meal of fat. Vitamin A was added to the test meal as a chylomicron marker. Results: The following were significantly decreased in younger compared to older offspring: BMI, waist hip ratio, diastolic BP, fasting glucose, fasting TG (log transformed), VLDL apoprotein B, area under postprandial TG curve (log transformed) (all p<0.001), area under postprandial plasma and chylomicron retinyl palmitate curves (both p<0.01), and area under postprandial chylomicron remnant retinyl palmitate curve, VLDL TG (log transformed), and VLDL cholesterol (all three p<0.05). There were no significant differences in LDL cholesterol, HDL cholesterol, and fasting insulin between the two groups. After correcting for BMI and waist hip ratio, there were no significant differences between the two groups except for area under TG curve 1,097 ± 480 vs 2,208 ± 1,054 mg/dl•12 hr (mean ± 1 SD) and VLDL apo B 11.4 ± 3.2 vs 21.0 ± 7.6 mg/dl (both p<0.05). Conclusions: An increase in BMI and central fat deposition explains the increase with age in the above coronary risk factors, except for area under the TG curve and VLDL apo B. Independent changes in body fat and VLDL metabolism may be important in the age dependence of coronary artery disease.