The presence, implications, and approach to mitral valvular disease in the setting of a cardiomyopathy has recently become a focal issue for discussion. Although recent evidence suggests that mitral regurgitation confers a poor prognosis in heart failure, the true prevalence of mitral regurgitation as well as its pathogenic contribution to prognosis in heart failure remains uncertain. Whereas angiotensin-converting enzyme inhibitors have not been demonstrated to favorably alter mitral regurgitation, treatment with b-blockers or cardiac resynchronization therapy has been shown to induce regression of ventricular dilation, with consequent decrease in mitral regurgitation. Surgical valve reconstruction by undersized ring annuloplasty appears promising, but optimal results require skilled surgical expertise. Even in highly experienced hands, intermediate outcomes appear to be inferior to those of cardiac transplantation. Percutaneous mitral valve repair remains an investigational procedure that warrants further clinical research.