The usefulness of two dimensional echocardiography in establishing the diagnosis of aortic dissection was evaluated. Forty-two patients were referred for study; 15 had a dissection and 27 did not. Two dimensional echocardiography detected the intimal flap in 12 of 15 patients with a dissection, the three false negative studies were in patients with a localized dissection. There was one false positive study in the 27 patients who did not have a dissection.