Four hundred seven patients with aortic stenosis who had Doppler echocardiography before surgery were studied to determine the feasibility of Doppler-derived valve resistance calculation and its clinical value. Patients with milder aortic stenosis had lower mean gradient, larger valve area, and lower maximal resistance than those with severe stenosis. Maximal resistance was related strongly to aortic stenosis severity but did not add any information after valve area and gradient were known and was not related to surgical mortality.