The prevalence and severity of obesity are increasing in children and adolescents. This raises concerns about the accompanying cardiovascular complications. Such complications include hypertension, dyslipidemia, type II diabetes which may accelerate vascular disease, left ventricular hypertrophy and pulmonary hypertension due to obstructive sleep apnea. The evaluation of an obese child or adolescent should include careful consideration of these possible cardiovascular complications. If they are present, treatment should be directed at both obesity and the risk factor abnormality. This treatment may be important for prevention of future cardiovascular morbidity and mortality. In addition, research is necessary to better understand the mechanisms by which obesity increases the risk of cardiovascular disease.