The prevalence of obesity has increased over the past three decades, in children as well as in adults. When obesity develops in the childhood years, excess adiposity generally continues into adult years, and adult obesity with childhood onset is frequently more severe. The health consequences of obesity in adults are well established, including greater rates of hypertension, non-insulin dependent diabetes mellitus, and heart disease. This paper will discuss the risk factors for these adult disorders that are detectable in obese children. Compared to normal weight children, obese children have higher blood pressure, higher plasma insulin levels, and a more atherogenic lipid pattern. Thus, the characteristic features of Syndrome X, or the insulin resistant syndrome, can be detected in obese children and adolescents. The vascular consequences of exposure to these metabolic risk factors beginning in childhood have yet to be completely determined. However, it is very likely that childhood obesity does contribute significantly to cardiovascular disease. For these reasons, greater efforts should be mounted to reduce the currently rising rates.