As part of an epidemiological study on cardiovascular risk factors among children and adolescents in Navarra, 5,829 children were studied. These children, of both sexes, were between 4 and 17 years of age and were selected at random from the public and private school population in Navarra. The prevalence of hypertension (HT) was 7.17 +/- 0.34%, hyperlipemia (LDL/HDL > 2.2) 15.70 +/- 0.49% and obesity (Quetelet I) 3.96 +/- 0.26%. Of the children and adolescents in Navarra 23.68% show some of these three associated risk factors. Obesity was significantly associated with HT and hyperlipemia, measured by LDL/HDL > 2.2 (but not when defined by cholesterol > 200 mg/dl). This association was greater when the pathology was defined by the Quetelet Index, rather than by the skinfold thickness. Hypertension was not associated with hypercholesterolemia (defined as LDL/HDL > 2.2). The association with hyperlipemia (measured by LDL/HDL) disappeared when the obesity effect was eliminated. It is deduced from these factors that if we don't take preventative health measures, the present children and adolescents from Navarra will suffer a high cardiovascular morbi-mortality when they become adults.