The pulmonary venous vascular volume and its compliance (PVcomp) are important factors influencing filling of the left ventricle. It seems that a poor PVcomp effects the value and reversibility of secondary pulmonary hypertension. Basing on Hirakawa's method PVcomp (= 0.4'' x SV/V-d) was calculated in 34 patients with isolated mitral stenosis (SM). Basing on the mean value of PVcomp the group was divided into those with poor (< = 4.3 ml/mmHg) and good (4.4 and more ml/mmHg) PVcomp. Prior mitral valve replacement (MVR) the groups did not differ in values of PAP, PWP, SVI, PVR assessed at rest. During exercise (25 Watt) in the supine position significant higher values of PAP and PWP were observed in patients with poor compliance. Six months after MVR the PAP and PWP values normalized in all patients. In the patients with the initial good PVcomp values significantly higher values of SVI and a decrease in PVR was found. During exercise (25 Watts) significantly higher values of PAP and PVR were registered in patients with initial poor PVcomp values. Pulmonary venous compliance may be an independent factors influencing the clinical outcome of mitral valve replacement 6 months after the procedure.