Hypercholesterolemia is a major cardiovascular risk factor. This study aimed to assess serum total cholesterol (TC) levels of children and adolescents living in Bangkok, Thailand. During 1995-1997, nonfasting blood samples were obtained from 570 healthy school children and adolescents aged 9-18 years. The mean TC levels ranged from 143-180 mg/dl in males and from 145-202 mg/dl in females. The prevalences of hypercholesterolemia (TC > or = 200 mg/dl) were 12.2 per cent and 20.3 per cent in males and females, respectively. Twenty-eight per cent of males and 26.9 per cent of females had borderline values (TC 170-199 mg/dl). TC inversely correlated with age (r = -0.16, P < 0.01) in males. The findings indicate that notable percentage of these children had elevated cholesterol levels and warrant additional study concerning risk factors and tracking of lipoprotein levels from childhood into adulthood.