The hemodynamic results after prosthetic tricuspid valve replacement were investigated in 8 patients. One patient had myxoma in the right atrium with destruction of the tricupsid valve. 7 patients had multiple rheumatic valvular disease. In all these patients multiple valve replacement was performed. The pressure in the right and left atrium , the cardiac output, and stroke volume were determined in all cases at rest, in 5 patients also on exercise. Furthermore the subclavian venous blood flow was measured by Doppler ultrasound technique percutaneously. In all cases the pressure in the right atrium remained elevated after operation and increased on exercise with the increasing cardiac output. This pressure increase is due to an important obstruction of the prostheses to the blood flow. This could be demonstrated by determination of diastolic pressure gradients across the prostheses. In 5 cases the analysis of the pressure curves showed systolic elevation suspicious to tricuspid insufficiency. In all these cases a systolic regurgitation was seen in ultrasonic Doppler flow curves of the subclavian veins. This method seems to be of value in assessing tricuspid regurgitation after valve replacement. The hemodynamic results after prosthetic tricuspid valve replacement are unsatisfactory in most cases. Tricuspid valve replacement should be considered only in cases in whom valve-preserving procedures are not possible.