Mitral regurgitation (MR) is a common valvular disorder that has important health and economic consequences. Standardized guidelines exist regarding when and in whom to perform mitral valve surgery, but little information is available regarding medical treatment of MR. Many patients with moderate or severe MR do not meet criteria for surgery or are deemed to be at high risk for surgical therapy. We reviewed the available published data on medical therapy in the treatment of patients with primary MR. β-blockers and renin-angiotensin-aldosterone system inhibitors had the strongest supporting evidence for providing beneficial effects. β-blockers appear to lessen MR, prevent deterioration of left ventricular function, and improve survival in asymptomatic patients with moderate to severe primary MR. Angiotensin-converting enzyme inhibitor and angiotensin receptor blocker therapy reduces MR, especially in asymptomatic patients. However, in the setting of hypertrophic cardiomyopathy or mitral valve prolapse, vasodilators can increase the severity of MR. To define the precise role of medical therapy, a larger randomized controlled trial is needed to confirm benefit and assess in which subsets of patients medical therapy is most useful. Medical therapy in some patients improves symptoms, lessens MR, and may delay the need for surgical intervention.