Surgical ring annuloplasty is generally performed in patients with symptomatic atrial functional mitral regurgitation (MR) caused by long-standing atrial fibrillation (AF). However, its clinical results have not been well reported.Twenty consecutive patients with atrial functional MR (mean age of 68 ± 9 years) and a left ventricular (LV) ejection fraction (EF) greater than 50% underwent mitral annuloplasty. Concomitant procedures included tricuspid valve surgery in 16 patients, AF ablation in 13 patients, and coronary artery bypass grafting in 2 patients. We reviewed the clinical outcomes of those patients and investigated the specific preoperative echocardiographic findings related to MR recurrence.At discharge, the mean left atrial (LA) volume index and mean tricuspid regurgitation peak gradient had significantly decreased from 94 ± 59 mL/m 2 to 58 ± 30 mL/m 2 and from 34 ± 11mm Hg to 23 ± 5mm Hg, respectively. During the follow-up period of 28 ± 17 months, the New York Heart Association functional class significantly improved from 2.3 ± 0.6 to 1.3 ± 0.6. Four patients developed recurrent MR, and of those, two required reoperation. Those with recurrent MR had a significantly larger preoperative LV dimension than those without recurrent MR. Preoperative three-dimensional transesophageal echocardiography was performed in 12 patients, revealing a greater degree of leaflet tethering in patients with recurrent MR than that in patients without recurrent MR.In patients with the combination of atrial functional MR, left ventricular dilatation and excessive leaflet tethering, mitral annuloplasty alone may not be sufficient to achieve long-term correction of MR.