There is abundant evidence that the atherosclerotic process begins in childhood. Dyslipidemia is a major risk factor for atherosclerosis in adults and children. In the present study, we measured serum lipoprotein concentrations in 194 healthy children aged between 4 to 14 years. Children were grouped according to the socioeconomic status of the families, family history of essential hypertension and passive tobacco exposure. The values of total cholesterol, low density lipoprotein cholesterol and the ratio of total cholesterol/high density lipoprotein cholesterol in the low socioeconomic group were found to be significantly higher than the values obtained for the middle-high socioeconomic group. The values of total cholesterol, low density lipoprotein cholesterol, the ratio of total cholesterol/high density lipoprotein cholesterol and low density lipoprotein cholesterol/high density lipoprotein cholesterol in the passive smoker group were found to be significantly higher than those of the nonsmoker group. But, the socioeconomic level in the passive smoker group was found to be significantly lower than that of the nonsmoker group, and therefore, the impact of passive smoking on the serum lipids in children was related to socioeconomic status. A significant difference in terms of blood lipid fractions between the groups with and that without a family history of essential hypertension was not found. These results suggest that passive smoking and lower socioeconomic status are important risk factors for cardiovascular heart disease, while a positive family history of essential hypertension is not an important risk factor.