Early childhood overweight and obesity have alarmingly increased over the years. Adulthood obesity is a well demonstrated significant independent predictor of cardiovascular risk (CVR) and/or mortality, which predisposes to the major components of metabolic syndrome (MS). Evidence of MS in obese children has been also reported associated with biochemical and inflammatory factors that affect vascular physiologic function. Assessment of vascular function can be measured noninvasively in children allowing early detection of endothelial dysfunction and severe increase of arterial stiffness before clinical manifestations of atherosclerosis. Impairment of endothelial function related to the severity of obesity and to the degree of insulin resistance is considered as a condition that confers a premature atherogenicity status and is linked to adult conventional cardiovascular risk factors. Adipose tissue factors that interfere with insulin action and endothelial cell function have also been identified as major precursors of CVR factors. The metabolic and cardiovascular consequences of childhood obesity are well demonstrated and have a major impact on the development of atherosclerosis and lifetime CVR. The development of programs involving both diet and exercise for children with overt overweight/obesity appears to be essential to improve vascular function and metabolic disorders. Such interventions should be complemented by a primary prevention against childhood obesity.