Hypercholesterolemia has been known to be an important factor in the development of atherosclelosis. Blood cholesterol screening and related health education in children, however, have not yet been widely practiced in Japan. From 1985 to 1990, blood samples were obtained from 5825 school children aged 6 to 14 years residing in Hisayama, Japan. The mean total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C) levels were determined. The mean TC levels ranged from 155 to 172 mg/dL for boys and from 156 to 170 mg/dL for girls, peaking at 9 years for both sexes. The TG levels also tended to increase gradually and to peak at 11 years for both sexes. The tendency for TG levels to be higher was much clearer than in US children and adolescents. The HDL-C levels were highest at 9 years of age for both sexes and the LDL-C levels also tended to peak at 9 years of age for boys and at 8 years of age for girls. Atherogenic Indices [(TC-HDL-C)/HDL-C] ranged from 1.7 to 1.9 for boys and 1.8 to 2.0 for girls. As the cholesterol level of Japanese children would be expected to rise steadily reflecting their westernized lifestyle, preventive programes on a nationwide base including health education at school environments should be emphasized.