As part of an epidemiological study on cardiovascular risk factors among children and adolescents in Navarra, lipids and lipoproteins were analyzed in 5,829 children of both sexes. These children were between 4 and 17 years of age and were randomly selected from the school population of our community. In this article, we analyze the prevalence of lipid risk, according to its different definitions, among children and adolescents in Navarra, and its variations related to age, sex and sanitary area. The prevalence of hypercholesterolemia (C > 200 mg/dl) among children and adolescents, aged 4 to 17 years, is very high: 21.07% +/- 0.54%. In spite of having high serum levels of HDL, the lipid risk measured by the risk quotient LDL/HDL > 2.2 is still very high: 15-70% +/- 0.49%. If we define the lipid risk during childhood and adolescence by the quotient LDL/HDL > 2.2, male adolescents turn out to be the group with the highest risk. This phenomenon coincides with the results of the epidemiological studies made among adults. Nevertheless, they do not coincide with these results if the lipid risk is defined by C > 200 mg/dl. In our opinion, during infancy and adolescence, the lipid risk is better defined by the quotient LDL/HDL > 2.2.