Obesity is pathogenically related to clinical and subclinical disorders that contribute to the development of atherosclerotic plaques and their complications leading to onset of cardiovascular events. Arterial stiffness may be an indicator of early vascular changes signaling the development of vascular disease. The purpose of this study was to assess the stiffness of the abdominal aorta using transthoracic echocardiography in normotensive obese and hypertensive obese pediatric patients and a control group. The study group consisted of 25 healthy children (M/F: 13/12) as a control group (Group I), 25 normotensive obese children (M/F: 13/12) (Group II) and 25 hypertensive obese children (M/F: 14/11) (Group III). The mean ages were 12.1 +/- 1.8, 11.9 +/- 1.5 and 12.4 +/- 1.4 years, respectively. Aortic strain (S), pressure strain elastic modulus (E-p) and normalized E-p (E-p*) measurements were significantly different in the hypertensive obese group, and cholesterol levels and body mass index were higher in this group. These findings may be important in determining the relationship between obesity and cardiovascular risk factors at pediatric age.