Percutaneous mitral valvuloplasty (PMV) is an effective therapy in patients with significant mitral stenosis. Few studies have examined the effect of mitral regurgitation (MR), a frequent periprocedural finding, on PMV outcomes. We examined the effects of pre- and postprocedural MR after PMV. Contrast left ventriculography was performed before and after PMV, and the MR severity was assessed using Sellers' classification. Clinical, hemodynamic, and morphologic variables were collected for all patients. Consecutive patients (n = 876) undergoing a first PMV procedure at a single tertiary center were evaluated. An increasing preprocedural MR severity was associated with reduced PMV success (no MR, 75%; 1+ MR, 65%; 2+ MR, 44%; p <0.0001), increased in-hospital mortality (0.6% vs 2.8% vs 4.9%, respectively; p = 0.007), and other complications. Increasing grades of pre- and postprocedural MR predicted, independently and in a grade-dependent manner, the composite outcome of mortality, mitral valve surgery, or redo PMV (preprocedural MR >or=1+, relative risk [RR] 1.4, 95% confidence interval [CI] 1.2 to 1.8; preprocedural MR >or=2+, RR 1.6, 95% CI 1.1 to 2.4; postprocedural MR >or=1+, RR 1.6, 95% CI 1.2 to 2.0; postprocedural MR >or=2+, RR 2.2, 95% CI 1.7 to 2.7; and postprocedural MR >or=3+, RR 4.6, 95% CI 3.4 to 6.2, respectively). In conclusion, increasing pre- and postprocedural MR grades independently predicted the long-term clinical outcomes after PMV. Patients with moderate preprocedural MR, in particular, appeared to have suboptimal short- and long-term outcomes, necessitating careful monitoring and early referral for mitral valve surgery, when appropriate.