Functional mitral regurgitation (FMR) is a distinctive valve disease in which the left ventricle is the "culprit" and the mitral valve is the "victim". It differentiates from organic regurgitation because the structure of the valve and subvalvar apparatus are not affected, hence abnormalities of the left ventricle are not the consequence but the cause of valve disease. It is at present well known that FMR conveys adverse prognosis in patients with left ventricular dysfunction, with a graded relationship between severity and reduced survival. Recent important advances in the understanding of pathophysiology of this complex valve disease have recognized that FMR results from changes in the geometry of the left ventricle, the mitral annulus and papillary muscles. Assessment of the degree of FMR, by Doppler echocardiography, has allowed to identify patients with adverse prognosis and predictors of death, drawing guidelines for therapy. Standard surgical restrictive annuloplasty represents the treatment of choice, although improvement in long-term survival had not been clearly demonstrated yet. New surgical and interventional therapies are currently under development. In this paper we reviewed the most important published literature, trying to define the mechanisms of regurgitation, diagnosis and therapeutic options, making an update of future perspectives for the treatment of FMR.