BACKGROUND: The patients with mitral stenosis are generally accompanied with impaired pulmonary function. The aim of this study was to evaluate the changes of pulmonary function after percutaneous mitral balloon valvuloplasty (PMV) in that patients. METHODS: PMV was performed in 36 patients with mitral stenosis in Pusan National University Hospital and hemodynamic, echocardiographic and pulmonary function test data before and after PMV were analyzed. RESULT: After PMV, NYHA functional class was improved from 2.2+/-0.6 to 1.2+/-0.4 (p<0.001). The mean left atrial pressure and mean pulmonary arterial pressure significantly decreased from 14.5+/-6.2 mmHg to 5.7+/-4.4 mmHg(p<0.001) and from 25.3+/-10.9 mmHg to 15.5+/-7.4 mmHg (p<0.001), respectively. Cardiac output was slightly decreased from 5.34+/-1.31 L/min to 5.28+/-1.25 L/min (p=0.50). Mean mitral pressure gradient decreased from 13.5+/-5.8 mmHg to 4.4+/-2.1 mmHg (p<0.001) and mitral valvular area significantly increased from 0.86+/-0.19 cm2 to 1.71+/-0.28 cm2 (p<0.001). In pulmonary function test, only MVV and PEF was significantly improved from 77.2+/-23.8% to 88.4+/-27.9% (p<0.01) and 87.1+/-26.8% to 97.5+/-26.4% (p<0.01), respectively. But, VC, FEV1, FEF25-75% and FVC were not changed significantly. In exercise treadmil test, exercise duration was significantly improved from 482.0+/-266.2 sec to 718.0+/-287.5 sec (p<0.001). CONCLUSION: We observed the results of better hemodynamic changes and exercise capacity after PMV. But, there was no significant improvement in pulmonary function after PMV. In our opinion, irreversible pulmonary changes and hemodynamic effect on pulmonary function should be considered.