Objective: Abnormalities of the aortic root and ascending aorta are common in patients with a bicuspid aortic valve (BAV). The aim of this study was to evaluate the stiffness of the abdominal aorta in children with BAV. Materials and Methods: In this cross-sectional observational study, we evaluated 35 children with normally functioning or mildly regurgitant BAV and 35 healthy children as controls. All children were noninvasively evaluated with transthoracic echocardiography. Annulus of aorta and abdominal aorta diameters were measured. Aortic strain (S), pressure strain elastic modulus (Ep), pressure strain normalized by diastolic pressure (Ep*), aortic stiffness β index (βSI) and, aortic distensibility (DIS) were calculated using the measured data. In evaluation of the data Student’s t-test, Chi-square test, Pearson’s correlation and multivariate linear regression analysis were used. Results: Diameter of the aortic annulus was found significantly larger in the children with BAV than the control group (p<0.05). The abdominal aorta systolic and diastolic diameters were similar in the two groups (p>0.05). The children with BAV exhibited significantly lower S (0.210±0.04/0.267±0.07, p<0.001) and DIS (1.04±0.2/1.4±0.4 10-6 cm2 dyne-1, p<0.001); and higher Ep (200±39/153±47 N/m-2, p<0.001), Ep* (3.42±0.9/2.5±0.9, p<0.001) and βSI (1.1±0.3/0.84±0.3, p<0.001) than the control group. There was no correlation between the systolic and diastolic diameters of abdominal aorta and aortic elasticity parameters (p>0.05). Conclusion: Bicuspid aortic valve is associated with an increased abdominal aortic stiffness in children. However, impaired abdominal aortic elasticity is not due to abdominal aortic dilatation. These findings require validation by further studies.