Background Aortic root disease and aortitis with or without aortic regurgitation are well recognized complications in patients with ankylosing spondylitis(AS). We were to determine the subclinical aortic disease including aortic root and descending thoracic aorta and aortic stiffness using transesophageal echocardiography(TEE) in young patients with diagnosed AS less than 15 years and compare the results with controls. Methods Sixty AS patients (aged 28짹5 years) and 26 age-matched healthy volunteers (aged 26짹3 years) underwent TEE. All subjects were male. Results Of the AS patients, 49(82%) were positive for HLA-B27 and 24(40%) had history of uveitis. The patients with AS were all diagnosed less than 15 years with mean duration of 5.6 years. Aortic root wall and mitral leaflet were more thickened significantly in patients than in controls (p<0.001). No significant valvular regurgitation was seen. Diameter of aortic root and descending thoracic aorta, and aortic stiffness (beta index) and elasticity (aortic strain and aortic distensibility) were not different significantly between patients and controls. Aortic root and valve disease were unrelated to the disease duration, activity or severity of AS. Conclusion Aortic root and mitral valvular thickness were more increased in young patients with AS diagnosed less than 15 years than controls, but significant valvular regurgitation and abnormal aortic stiffness and elasticity were not observed. This subclinical aortic disease should be followed up to determine its prognostic implication and evolution.