Clustering of selected coronary heart disease (CHD) risk factors was studied in a cohort of 3457 children and adolescents, aged 3-18 years. Subjects were defined as "high-risk" individuals if their values for serum LDL cholesterol, systolic blood pressure and obesity index (sum of biceps, triceps and subscapular skinfolds) exceeded the age- and gender-specific 75th percentile of the present study cohort. Clustering was studied by using the observed/expected ratio (O/E ratio). Statistically significant clustering was observed as 3.1% of all subjects belonged to the high-risk group (O/E ratio = 2.0, p