The potential of transoesophageal echocardiography for preoperative diagnosis of thoracic aorta pathology was evaluated in 15 patients with aortic dissection and 15 patients with aortic aneurysm. The transoesophageal echocardiographic findings were compared with 14 computed tomograms and 21 angiograms. Six patients underwent only transoesophageal echocardiography. All patients were operated upon and the surgical findings were used as a reference for these diagnostic methods. Transoesophageal echocardiography established a complete and correct diagnosis in 27 patients. The diagnosis was partially correct in three patients, all having an aortic dissection. A complete and correct diagnosis was obtained by computed tomography and angiography in 8 and 17 patients, respectively. The results indicated that transoesophageal echocardiography is a sensitive and convenient method for the definitive diagnosis of pathology of the thoracic aorta. It could become the technique of choice in patients suspected of having acute aorta pathology as it enables a rapid and definitive diagnosis at the bedside.