A rare case of isolated tricuspid regurgitation (TR) in a 65-year-old man is presented. Echocardiography revealed dilatation of the tricuspid valve annulus, an intact atrial septum, and severe TR on color flow Doppler studies. Cardiac catheterization indicated elevated right atrial pressure with a pronounced V-wave. At surgery, severe annular dilatation of the tricuspid valve, without organically diseased or deformed tricuspid leaflets, was observed. Tricuspid annuloplasty with a prosthetic ring was performed with favorable results.