In 187 patients with combined mitral and aortic valve lesions, to assess and quantify tricuspid regurgitation, biplane right ventriculograms were obtained and Doppler echocardiography performed for study of the tricuspid valve and right atrium. After definition of regurgitant turbulance across the tricuspid valve with pulsed Doppler, on mapping the right atrium the maximal length of regurgitant flow in the right ventricular inflow tract was determined from the short-axis parasternal view. In seven of 70 patients in whom angiographically tricuspid regurgitation was not detected, Doppler echocardiography demonstrated holosystolic insufficiency of the valve. In all patients with the angiographic diagnosis of tricuspid regurgitation grades I to III, this lesion was also documented Doppler echocardiographically with only slight divergence of the regurgitant area in the right atrium as viewed from the short-axis parasternal transducer position. In all patients, the tricuspid valve was morphologically unremarkable. In 32 patients, in agreement with angiographic findings, grade I tricuspid regurgitation was diagnosed; in seven patients the angiographic severity was overestimated by one grade. In 44 patients, in agreement with angiographic findings, tricuspid regurgitation grade II was detected; in four patients the Doppler echocardiographic severity was overestimated and five patients underestimated by one grade. In 23 patients with grade II tricuspid regurgitation angiographically, there was agreement with Doppler echocardiographic findings; in two patients the severity was underestimated by one grade.(ABSTRACT TRUNCATED AT 250 WORDS)