Cardiac catheterization (CC) was done in 525 symptomatic patients. Tricuspid regurgitation (TR) was graded from right ventricular (RV) angiography (RVA) and compared with RV indicator curves (IC). Tricuspid stenosis (TS) was diagnosed from the mean diastolic gradient (MDG). Organic (O) disease was diagnosed from TS or from thickening of the tricuspid valve (TV) on angiography. TR was found in 137 patients (26%), of whom 46 (33.5%) had additional TS. All of the patients with TS had significant TR. OTR was more frequent (70.4%) and more severe (p less than 0.0001) than functional TR (FTR). There was no difference in pulmonary artery pressure between FTR and OTR except when associated with TS. The TV was explored in 56 patients. A MDG greater than or equal to 2 mm Hg correctly predicted TS in 91% of the patients and right atrial angiography in 100% of the patients. Organic thickening of the TV was predicted in 84%.