Fifty-three patients with mitral stenosis (MS) were examined by two dimensional (2DE) and Doppler echocardiography (Dop). Twenty-nine of them also had mitral insufficiency (MI) as judged by Dop. The mitral valve area (MVA) was calculated from Doppler using the "pressure half time" and was compared with MVA by 2 DE. There was a good correlation between both methods in all 53 patients (r = 0.88; SEE = 0.34 cm2) but also in the subgroups with pure MS (r = 0.86; SEE = 0.29 cm2) and MS + MI respectively (r = 0.90; SEE = 0.38 cm2). The accuracy and the reproducibility of the Doppler method was highly dependent on the severity of the stenosis. In 19 cases with mild MS (MVA by 2 DE greater than 1.5 cm2) the absolute difference between MVA 2 DE and Dop averaged 0.39 cm2. The difference between the maximal and minimal Doppler MVA which reflects the variability of this method averaged 0.65 cm2 in this group. In cases with significant MS (MVA by 2 DE less than or equal to 1.5 cm2) the average difference 2 DE -Dop and Dop max-Dop min was only 0.20 cm2 and 0.27 cm2 respectively. In patients with comparable degrees of stenosis additional MI did not adversely affect the accuracy of the Doppler method. We conclude that Doppler echo allows an accurate quantitation of mitral stenosis even in patients with associated MI.