To determine the relative sensitivity and specificity of noninvasive methods for detecting aortic insufficiency, we compared the accuracy of auscultation, echocardiography, and pulsed Doppler echocardiography in detecting aortic insufficiency in 106 patients in whom the presence or absence of the lesion was shown by supravalvular aortography. The sensitivity and specificity for the diagnosis of aortic regurgitation was 96% and 96% for pulsed Doppler echocardiography, 73% and 92% for auscultation, 43% and 91% for two-dimensional echocardiography, 46% and 81% for anterior mitral leaflet flutter, and 9% and 96% for ventricular septal flutter, respectively. Auscultation was more sensitive than either M-mode or two-dimensional echocardiography in the diagnosis of aortic insufficiency (p less than 0.01). Pulsed Doppler echocardiography was significantly more sensitive than auscultation (p less than 0.0001) and was positive in 19 patients in whom no murmur was found. Thus, pulsed Doppler echocardiography is the optimal noninvasive marker for aortic insufficiency.