PBMV is a catheter-based approach to nonsurgically relieving obstruction to mitral inflow in patients with symptomatic mitral stenosis. Since 1986, 50 patients at the Mayo Clinic have undergone the procedure, utilizing either the Inoue pillow-shaped balloon or a dual-balloon technique with excellent early hemodynamic and symptomatic results. Mean mitral valve area increased from 1.06 +/- 0.32 cm2 to 2.01 +/- 0.70 cm2, and transmitral gradient decreased from 15.7 +/- 7.1 mm Hg to 7.5 +/- 3.9 mm Hg. This improvement has been sustained during short-term and intermediate-term follow-up. A marked improvement in procedural success and complication rates is attributable to refinement of patient selection criteria, technical advances in the procedure, and operator experience. There have been three procedure-related deaths; one of these was in a patient who developed severe mitral regurgitation after PBMV and underwent emergency valve replacement. Unfavorable outcomes appear to be related to three factors: presence of thick, calcified valve leaflets with extensive subvalvular involvement, poor general medical status, and operator inexperience.