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 using transesophageal echocardiography(TEE) in young patients with diagnosed AS less than 15 years and compare the results with controls.MethodsTwenty-two AS patients (aged 28.0짹5.3 years) and 14 age-matched healthy volunteers (aged 25.7짹2.7 years) underwent TEE. All subjects were male.Results Of the AS patients, eighteen(82%) were positive for HLA-B27 and 9(41%) had history of uveitis. The patients with AS were all diagnosed less than 15 years with mean duration of 6.1 years. Aortic root wall and mitral leaflet were more thickened significantly in patients than in controls (p<0.001). Ascending aortic diameter was more dilated in patients than in controls (p=0.03). No significant valvular regurgitation was seen. Diameter of aortic root and descending thoracic aorta were not different 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 and ascending aortic diameter are more increased in young patients with AS diagnosed less than 15 years than controls, but significant valvular regurgitation was not observed. This subclinical aortic disease should be followed up to determine its prognostic implication and evolution.