Aortic dissection, especially type A, is a life-threatening condition, that requires a prompt and accurate diagnosis to ensure a rapid and precise therapeutic approach. Transesophageal echocardiography (TEE) is a highly reliable technique because of its sensitivity and specificity (near 100%; almost similar to nuclear magnetic resonance), and because it is a very low risk, rapid and easy diagnostic tool. Two hundred sixty-one patients were admitted at our institution in a 6-year period (1988-1994), because of a suspicion of aortic dissection. Two hundred forty-seven of them were submitted to TEE and the diagnosis was compared with surgical data in 124. There was only one false positive by TEE. Sensitivity of TEE vs surgery was 100%, specificity 93.7%, diagnostic accuracy 99%. Agreement between TEE and surgery in the setting of intimal tear was 69.2%. These data confirm the usefulness of TEE in the diagnostic approach to aortic dissection and the therapeutic decision, without using other methods.