Present day indications for surgery in mitral regurgitation have to take into account changes in aetiology, advances in pre-operative evaluation of mitral lesions, technical progress in mitral valve repair and better knowledge of pre-operative predictive factors of surgical results. The results of a series of 294patients operated on between 1970 and 19 show that surgery b advbable before patients reach Functional Class III or IV, and before they develop atrial fibrillation, an ejection fraction of under 0.5, or marked left ventricular and atrial enlargement. Surgical indications depend on two factors: the possibility of valve repair evaluated by transthoracic and transoesophageal echocardiography, and the experience of the surglcal team in this kind of surgery. Valve repair is the best treatment in many patients, particularly those with degenerative valve lesions, poor ejection fraction, elderly people and some cases of infective endocarditis.