This study verified the usefulness of two-dimensional (2-D) and pulsed Doppler echocardiography (PDE) in the diagnosis of tricuspid stenosis (TS), and estimated the diastolic pressure gradient (PG) across the tricuspid valve (TV). Fifty-two patients with rheumatic mitral stenosis showing a decreased EF slope of the TV less than 40 mm/sec were studied. All patients underwent cardiac catheterization, and the mean diastolic pressure gradients (PG) across the TV were calculated with simultaneous recordings of right atrial and ventricular pressures. Based on surgical findings, all patients were categorized as the TS group consisting of 10 patients with TS (mean PG less than or equal to 5.0 mmHg; seven patients, greater than 5.0 mmHg; three patients), and the non-TS group consisting of 42 patients without TS. In three patients with PG exceeding 5 mmHg, the TV disclosed typical commissural fusions between the leaflets. 1. 2-D echocardiography The diagnosis of TS was made by recording diastolic doming and thickening of the TV in the parasternal long-axis and apical 4-chamber views. Among the 52 patients, 2-DE detected stenosis in all 10 patients with TS, for a sensitivity of 100%, while excluding TS in 40 of 42 patients without TS for a specificity of 95%. 2. Pulsed Doppler echocardiography The transtricuspid flow velocity in diastole was recorded from the apical window.(ABSTRACT TRUNCATED AT 250 WORDS)