PURPOSE: Obesity is closely related to insulin resistance, compensatory hyperinsulinemia and dyslipidemia in adults. We identified the effect of obesity measured by BMI and insulin resistance on dyslipidemia in children and adolescents. METHODS: The fasting serum insulin, glucose, total cholesterol, triglyceride, HDL- and LDL-cholesterol were measured and insulin resistance(HOMA-IR) was calculated in 35 children with simple obesity(age : 10.6+/-2.8 years; male 20, female 15; BMI : 27.1+/-5.4 kg/m(2)). RESULTS: The hypertriglyceridemia(37%), hyperinsulinemia(54%) and HDL-hypocholesterolemia(5.7 %) were observed. HOMA-IR was well expressed by fasting insulin. As BMI increased, there was a statistically significant increase in insulin resistance and insulin level in both sexes. BMI was not related with lipid profile in both sexes. Triglyceride was correlated with only insulin level and insulin resistance index in boys. In girls, there was no correlation between triglyceride, HDL-cholesterol and insulin(insulin resistance). CONCLUSION: These results suggest that hypertriglyceridemia was dependent on insulin resistance in pre-adult males. Monitoring of insulin resistance and those risk factors known to become a part of insulin resistance syndrome should become part of routine medical care for obese children.