The anatomy of the mitral leaflets, a classification of the variations in pathologic morphology of rheumatic stenosis, and the evolution of a practical technic for relief of that stenosis while restoring valve action are considered. The life cycle of patients suffering from mitral stenesis is reviewed and a clinical classification of these patients is presented. Some indications and contraindications for surgery are discussed in the light of strength and weakness of present surgical methods. Results of surgical treatment are reviewed.