In 40 patients aged 25-52 years (mean 36 years) with mitral valve disease but without overt circulatory failure haemodynamic studies and echocardiographic examinations were carried out recording the blood flow in the pulmonary artery and the blood flow through the tricuspid valve by pulsating and continuous-wave methods. From the obtained curves the time was calculated from the beginning of the flow to its maximum (TPV), the pre-ejection time (RPEP) and the right-ventricular ejection time (RVET), and the indices TPV/RVET and RPEP/RVET. Moreover, in 14 patients with coexistent insufficiency of the tricuspid valve the systolic pressure in the pulmonary artery was calculated by determining the systolic gradient across the tricuspid valve. On the basis of the results of haemodynamic examination the patients were divided into two groups: with normal (24 patients) and with raised (16 patients) pressure in the pulmonary artery. In the group of mitral valve disease and pulmonary hypertension a significantly shorter TPV, lower values of the TPV/RVET index and greater values of the RPEP/RVET index were found as compared with the patients with mitral disease and normal value of the systolic arterial pressure in the pulmonary artery. The systolic arterial pressure in the pulmonary artery determined on the basis of Doppler echocardiography with measurement of the regurgitation wave in tricuspid valve insufficiency showed a high agreement (r = 0.94) with the pressure recorded during cardiac catheterization.