Decreased operative risk of surgical treatment of mitral regurgitation with or without coronary artery disease. The consecutive 2 year experience with patients undergoing first-time surgery for mitral regurgitation with and without coronary artery disease was reviewed. From January 1988 to January 1990, 127 patients with pure mitral regurgitation undergoing first-time operation were surgically treated. No other valve lesion, no reoperation and no congenital defects were included. The mean patient age was 62 years with 26% of the patients greater than 70 years. Twenty-six percent of the entire group was in functional class IV. Seventy-five patients received mitral valve repair and 52 underwent mitral valve replacement with a St. Jude or Hancock valve. In patients undergoing mitral valve repair, there was a higher incidence of those greater than 70 years old and of coronary artery disease and in patients undergoing mitral valve replacement there was a higher incidence of functional class IV. The operative mortality rate was 2.3% (3 of 127 patients). No patient failed to be discontinued from cardiopulmonary bypass and all three deaths occurred after mitral valve replacement, with one from complications of chronic renal failure and dialysis. There was no significant difference in patients who either did or did not have a concomitant coronary artery bypass graft and there was no difference related to age or functional class. Postoperative complications occurred in five patients in the valve repair group, including recurrent mitral regurgitation in two necessitating reoperation, and in three patients in the valve replacement group. With newer operative and postoperative management techniques, especially preservation of the papillary muscle annular continuity, the risk of mitral valve surgery, particularly of valve repair, is considerably lower than in previous years. 