The aortic valve orifice area was measured in 95 patients with valvular aortic stenosis by means of transthoracic and transesophageal echocardiography. These results were compared to invasively determined measurements. The aortic-valve orifice area could be measured by transesophageal echocardiography in 87 patients (92%), and in 13 patients (14%) by the transthoracic approach. A comparison of the valve-orifice area determined by transthoracic and transesophageal echocardiography revealed a correlation coefficient of r = 0.91. There was also a good agreement when the aortic-valve orifice area determined by transesophageal echocardiography was compared to the invasive findings (r = 0.82; p less than 0.001). The morphology of the aortic valve could be better delineated with the transesophageal approach.