The purpose of this longitudinal study was to identify factors for coronary artery disease (CAD) in a teenage population in the Netherlands from ages 13.5 to 21.5 years. In a follow-up study 93 boys and 107 girls were measured annually from 1977 to 1980, and a fifth measurement was made in 1985. The CAD factors assessed were total serum cholesterol (TC), high density lipoprotein cholesterol (HDL), TC/HDL ratio, systolic (Psyst) and diastolic (Pdiast) blood pressure, percentage body fat (percent fat) and aerobic fitness (VO2 max/BW). The results indicate that the percentage of subjects at risk for CAD are relatively low in both sexes for all factors except for percent fat. From 20 to 30% of the subjects remain in the upper half of risk factor distribution throughout the 8 years study for TC, TC/HDL, percent fat, and VO2max/BW, indicating stability during the teenage period. Because percent fat combines a high stability with relatively high mean values during the teenage period in both sexes, this parameter seems a particularly important CAD risk factor in youngsters.