Background: We sought to determine if echo-Doppler derived pulmonary vascular resistance (PVR) and tricuspid annular velocity (TAV), as determining parameters of right ventricular (RV) perforamnce, have value on predicting the cardio-pulmonary exercise (CPX) capacity in patients with mitral stenosis (MS). Method: Thirty-six patients (23 female, age 52.5짹8.8 years) with moderate to severly stenotic mitral valve (effective mitral orifice area (EOA):0.8-1.5 cm2 ) were studied. Exclusion criteria included patients with left ventricular (LV) systolic dysfunction (ejection fraction (EF) < 50%), valvular heart disease other than secondary tricuspid regurgitation (TR), congenital heart disease and chronic pulmonary disease. Resting echo-Doppler derived PVR, defined as peak TRvelocity/TVI RVOT (time-velocity integral at RV outflow tract), TAV, net atrio-ventricular compliance (Cn), left atrial volume index (LAVI), transmitral mean diastolic pressure gradient (MDPG) and cardiac output (CO) were measured. Symptom-limited exercise test was performed with bicycle ergometer. Blood pressure and Doppler-derived PVR and CO were calculated at each stage of exercise. As parameters of exercise capacity, CO at peak exercise, VO2 max, predicted VO2 max (%), and ratio ventilation to CO2 output (Ve/VCO2) at anaerobic threshold (AT) were measured. Measurements during ���5 cardiac cycles representing the mean heart rate were averaged. Results: Doppler-derived PVR was inversly correlated with peak systolic tricuspid annular velocity (Sa) (r= -0.491, p=0.008) and Cn (r= -0.378, p <0.05). In multivariate analysis, decrease of resting and peak Sa and increase of resting and peak PVR were significantly related with impairment of CO increase, VO2 max (r=0.398, p<0.05 for Sa and r=-0.424, p<0.05 for PVR) and Ve/VCO2 slope (r=-0.412, p<0.05 for Sa and r=0.401, p<0.05 for PVR). However, resting EOA, transmitral MDPG, and peak TR velocity were not significantly related with CPX capacity. Conclusions: Echo-Doppler derived PVR and Sa have independent value on predicting the CPX capacity in patients with MS.