Mitral regurgitation commonly occurs in patients with heart failure. Systolic dysfunction is the hallmark of dilated cardiomyopathy. Mitral functional regurgitation is mitral incompetence in the absence of intrinsic lesions of the mitral valve apparatus. Echocardiography can make a major contribution to the diagnosis of cardiomyopathies. A more careful anatomic and hemodynamic evaluation of mitral regurgitation mechanisms is possible with spectral Doppler, color Doppler, three-dimensional echocardiography and transesophageal echocardiography. Functional mitral regurgitation is due to the incomplete closure of mitral leaflets and is based on alterations of mitral annulus, left ventricular dimensions, function and geometry, left atrial dimensions and function. Knowledge of the mechanisms of mitral regurgitation helps us to gain an insight into therapeutic interventions that modify the mechanistic factors. Medical therapy reduces the tethering forces and also augments transmitral pressure; surgical approaches can modify geometric relationships in the left ventricular chamber and resynchronization therapy can improve co-ordinated timing of mechanical activation of papillary muscles.