BACKGROUND Recent advances in the field of echocardiography have made it possible to obtain a complete morphological and hemodynamic assessment of patients with aortic stenosis. Therefore, comprehensive two-dimensional and Doppler examinations were performed on patients with aortic stenosis returning for the Second Natural History Study of Congenital Heart Defects (NHS-2). RESULTS Two hundred thirty-two patients with aortic stenosis underwent comprehensive two-dimensional and Doppler examinations. Of these, 96 were in the medically treated group, 49 had undergone aortic valve replacement, and 87 had had aortic valvotomy. The valve replacement group had a significantly smaller left ventricular diastolic cavity than did the medically treated group; both had smaller dimensions than the valvotomy group. There was no significant difference in left ventricular wall thickness or fractional shortening among the three groups. The valvotomy group had a significantly higher mean aortic valve gradient than did either the medically treated group or the valve replacement group. The degree of aortic regurgitation was more severe in the valvotomy group than in the other two groups. For all patients, there was a direct relation between the aortic valve gradient and the mean wall thickness and an inverse relation between the aortic valve mean gradient and fractional shortening. The only echocardiographic parameter that correlated with the presence or absence of symptomatology was the fractional shortening. CONCLUSIONS These observations provide an objective measurement for assessing the status of the aortic valve and left ventricular response in patients with aortic stenosis returning for NHS-2. Limitations of echocardiography in this study are discussed.