Cholesterol (CH) and triglyceride (TG) levels were determined in blood drawn after an overnight fast from 388 school children aged 5-19 years from private schools in Karachi. The mean CH levels ranged from 4.4 to 4.6 mmol l-1 (170.1 to 177.9 mg dl-1) for boys and 4.4 to 4.8 mmol l-1 (170.1 to 185.6 mg dl-1) for girls. The range of TG levels was 1.0 to 1.2 mmol l-1 (88.6 to 106.3 mg dl-1) and 0.9 to 1.1 mmol l-1 (79.7 to 97.4 mg dl-1) for boys and girls respectively. Sixty-two per cent of the girls and 54% of the boys had cholesterol values greater than or equal to 4.4 mmol l-1 (170 mg dl-1), a level at which dietary intervention is recommended for children. Thirty-two per cent of all the children had triglyceride levels above the 90th percentile of the levels for similar age groups in North America. The mean cholesterol intake was 469 mg/day for girls and 518 mg/day for boys. Overweight and inactivity were associated with raised serum cholesterol levels. Forty per cent of the girls and 25% of the boys reported a strong family history of hypercholesterolaemia and/or heart disease. The results show that the prevalence of hypercholesterolaemia is high in well-to-do Pakistani school children and factors which can be modified to lower serum cholesterol levels are identified