Twenty-nine patients with isolated (18) or predominant (11) mitral insufficiency were treated by mitral annuloplasty. This post-operative follow-up study, lasting from 3 to 5½ years (average 48 months), resulted in the following conclusions. The clinical, radiological, and electrocardiographic conditions usually followed a parallel course. Initial good results were maintained for up to 4 years in only 16 patients. Subsequent deterioration was related to progression to mitral stenosis (2 patients), recurrence of severe mitral insufficiency (13 patients), occurrence (5 patients) or recurrence (8 patients) of tricuspid insufficiency. Poor results were more often observed in the eldest patients, with conspicous pre-operative cardiac enlargement, atrial fibrillation, and long-standing cardiac failure. The indications for annuloplasty are reduced and apply primarily to mitral insufficiency without obvious cardiac enlargement, with normal sinus rhythm, and with short-standing congestive cardiac failure.