Over a period of 5.25 years, 1,530 patients with coronary artery disease (CAD) underwent catheterization; 104 had associated mitral regurgitation (MR), and 60 had no complications. Twelve patients underwent coronary artery bypass graft surgery (CABG), with both pre- and postoperative angiograms. Nine of the 12 patients (75 percent) were in functional class 3 or 4. Left ventricular ejection fraction ranged from 34 to 75. The MR was considered severe (3+) in three, moderate (2+) in six, and trivial (1+) in three patients. Following CABG, all except two patients were in class 1. Of the 43 patients medically treated, 31 patients (72 percent) were in functional class 3 or 4. Angiographic results showed that five patients had 3+ MR, 14 had 2+ MR, and 24 had 1+ MR. The EF was less than 30 in 23 patients and greater than or equal to 30 in 20 patients, and left ventricular filling pressure was elevated. Twenty patients died, with a mean follow-up period of 11 months. Our study demonstrates that the surgically treated patients showed angiographic improvement in MR, improved functional status, and relief of symptoms compared with medically treated patients. We believe that a subset of patients with MR and CAD would benefit with CABG.