The presented analysis includes the haemodynamic parameters obtained during right and left heart catheterization in 51 patients following mitral valve prosthetic replacement for rheumatic mitral disease within 1 month to 8 years. In 30 patients the examination was conducted pre- and postoperatively, and in 21--postoperatively only. A comparative analysis of the pre- and postoperative haemodynamic indices has shown that when the effect of surgery is positive, the pressure in the pulmonary artery, the wedge pressure, the right atrial, and the end-diastolic pressures in the right and left ventricles decrease. A reduction is also noted in the pulmonary-arteriolar resistance, in the arterio-venous oxygen content gradient, and in the right ventricle work, and an increase in the cardiac output, cardiac index and effective work of the left ventricle. The dynamics of these parameters is especially dramatic in patients with severe pulmonary hypertension (the pulmonary artery pressure falls by 60%, and the pulmonary-arteriolar resistance--by 83%). When the operation fails to produce any haemodynamic effect, the intracardiac haemodynamics disorders persist along with those in the pulmonary circulation, which permits us to find the reason of the unsatisfactory result of surgery.