The authors evaluated comparatively the results of surgical treatment of mitral stenosis in 203 patients after open mitral commissurotomy (OMC) (their personal experience) and the literature data concerning 168 patients who underwent closed mitral commissurotomy (CMC). The frequency of mitral stenosis recurrences with the use of both methods was determined. OMC was on a par with CMC in safety and exceeded it in efficacy. The frequency of mitral restenosis was considerably lower after OMC than after CMC (p less than 0.05). The authors claim that the main cause of mitral stenosis recurrences is residual stenosis developing in inadequate correction of the anomaly, while the principal preventive measure is OMC which makes it possible to separate the fused commissures completely, remove the subvalvar adhesions, and restore the mobility of the cusps.