Dyslipidemia is a major risk factor for atherosclerosis in adults and children. This study investigated the levels of lipoproteins in a northern Italian pediatric population, in relation to nutritional and familial factors. We studied 650 children on the basis of a 3-day dietary record; 361 of these children had their lipid levels [total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), and triglycerides] measured by a dry, multilayer method and apoprotein A-I and B by an immunonephelometric method. Familial history of cardiovascular disease and dyslipidemia was recorded. Anthropometric variables were taken for each child. Mean TC and low-density lipoprotein cholesterol (LDL-C) were high compared with southern Italian data, but similar to those of other Western countries. Family history of cardiovascular disease could not identify children with higher levels of atherogenic lipoprotein. Nutritional factors affected lipoprotein levels. The most important finding was a higher TC/HDL-C ratio in the lower quartile of polyunsaturated fatty acid intake. Obese children had higher levels of ApoB, triglycerides, TC and LDL-C, and lower levels of HDL-C; figures were higher for obese boys than for obese girls. Our study confirms a high prevalence of elevated levels of atherogenic lipoproteins among the northern Italian pediatric population and an association with nutritional factors and weight.