BACKGROUND: Rapid and accurate diagnosis is essential for successful management of acute aortic dissection. As transesophageal echocardiography(TEE) provides excellent imaging of thoracic aorta conveniently, TEE is widely indicated as a effective diagnostic method of aortic disease. To evaluate clinical usefulness of TEE in patients with suspected aortic dissection, we assessed diagnostic accuracy and feasibility of TEE. METHODS: Ninety-one consecutive patients with clinically suspected aortic dissection were examined by TEE, computerized tomography(CT), magnetic resonance imagion(MRI) and aortic angiography between August 1991 and September 1994. The diagnosis was confirmend by these techniques and surgery. RESULTS: 1) We diagnosed 27 proximal aortic dissection, 22 distal aortic dissection, 8 aortic intramural hematioma, 12 thoracic aortic aneurysm, 2 penetration ulcer, 1 necrotizing aortitis, 1 traumatioc aortic rupture and 18 normal findings in 91 study patients. 2) The sensitivity and specificity of TEE for aortic dissection were 98% and 97%, respecitively. The sensitivity and specificity of TEE to detect ascending aorta involvement were 94% and 100%. 3) CT was chosen in 62 cases as primary diagnostic method of aortic dissection, whereas TEE was performed in 21 cases. TEE was chosen as confirmative diagnostic method following CT in 45 cases, in one-third of whom TEE played a great role in diagnosis or decision of treatment modality. CONCLUSION: As TEE is and accurate and practical method in diagnosis of aortic dissection, TEE may be suggested as primary diagnostic method in suspected aortic dissection. TEE was also useful as confirmative diagnostic method complemention CT.