Percutaneous mitral commissurotomy (PMC) is currently the treatment of choice for patients with symptomatic mitral stenosis (MS) that have favorable valvular characteristics. We aimed to evaluate the effect of PMC on the longitudinal strain of the right ventricular (RV) free wall in patients with severe MS. This prospective study recruited patients who underwent PMC. Transesophageal and transthoracic echocardiographic examinations were performed. The mitral valve area (MVA) was measured by three-dimensional evaluation. The RV longitudinal strain was measured via the speckle-tracking method. A total of 42 patients with a maximum MVA of 1.5cm2 underwent PMC in our study. The MVA increased significantly after the procedure (pre-PMC MVA=0.94±0.20 cm2 vs post-PMC MVA=1.45±0.18 cm2 ; P<.01). Systolic pulmonary artery pressure decreased from 46.05±14.08mm Hg preprocedurally to 35.86±7.53mm Hg postprocedurally (P<.01). The mean RV free wall longitudinal strain was -19.00±5.14%, which rose significantly after PMC to -20.97±3.81 (P<.05). There were postprocedural increases, albeit nonsignificant, in the tricuspid annular peak systolic excursion, the peak systolic Doppler velocity of the RV free wall, and fractional area change. The improvement in the RV longitudinal strain was more prominent in the patients with an MVA of less than 1.0cm2 . There was a significant post-PMC rise in the RV free wall longitudinal strain measures in our study population, demonstrating an immediate improvement in the RV systolic function of the patients.