The Province of Luxembourg is an area in Belgium with a high prevalence of risk factors for cardiovascular disease and non-insulin-dependent diabetes mellitus among adults. In the present study, children in the age groups 6–8, 8–10, and 10–12 years were selected at random from school classes ( n = 1, 028), with a participation rate of 70.3%. Anthropometric factors, blood pressure, and fasting blood glucose, plasma cholesterol, triglyceride, and insulin levels were measured in 1992. All anthropometric and metabolic variables increased with age, except for waist: hip circumference ratio in boys and cholesterol in girls. In the oldest group, girts who had passed menarche were taller and heavier and had greater skinfold, body mass index, insulin, and systolic blood pressure values but lower total cholesterol levels and waist: hip ratios than girls who had not passed menarche. Boys had lower skinfolds and higher waist: hip ratios than girls in all age groups, and were significantly shorter and lighter in the oldest age group. There was no difference in body mass index between the two sexes. Girls had higher triglyceride and insulin levels in the 10- to 12-year age group, lower blood glucose values in the 8–10 and 10–12 age groups, and lower diastolic blood pressures in the 8–10 age group. Obesity, blood glucose, triglycerides, insulin, and blood pressure were highly interrelated. Cholesterol, triglycerides, insulin, and blood pressure values were all among the highest of values previously reported in other studies. The deciles of body mass index above 50 appeared to be particularly elevated, suggesting that obesity, when present, was pronounced in this population of children. These findings suggest an accumulation of genetic susceptibility to cardiovascular disease and non-insulin-dependent diabetes mellitus in this stable, ethnically homogeneous, and rather isolated part of continental Europe. Am J Epidemiol 1996; 144: 867-80.