Background. In patients requiring a second-time or more operation on the mitral valve (MV), we assessed whether the outcomes of the minimally invasive port access approach (port access group) were equivalent to those of the traditional redo sternotomy approach (redo sternotomy group). Methods. In a retrospective review (1998-2011), 409 patients had previous MV operations requiring a second-time or more MV reintervention. Of those, 67 patients had the port access approach, and 342 had the redo sternotomy approach. Of the latter, 220 met the inclusion criteria because emergencies, patients with endocarditis, and those requiring concomitant procedures involving aortic valve and aorta were excluded. Results. New York Heart Association class 2 or above, age, atrial fibrillation, and surgical indications were similar in both groups. The port access group had more patients with previous MV repair (78% [n = 52] vs 41% [n = 90], p < 0.01) than with MV replacement (19% [n =13) vs 53% [n = 116], p < 0.01). Concomitant procedures were similar (20% [n = 14] vs 27% [n = 59], p = 0.4). The MV re-repair rates were similar (19% [n = 10] vs 22% [n [20], p = 1). The cardiopulmonary bypass times (153 +/- 42 minutes vs 172 +/- 83 minutes, p = 0.07) and aortic cross-clamping times (104 +/- 38 minutes versus 130 +/- 71 minutes, p < 0.01) were lower in the port access group. Mortality was lower in the port access group, although not significantly (3.0% [n = 2] vs 6.0% [n = 13], p = 0.5). The rates of postoperative stroke were similar (3.0% [n [ 2] vs 3.2% [n = 7], p = 1). On postoperative echocardiography, freedom from mitral regurgitation >2+ was 100% in the port access group and 99% in the redo sternotomy group. The mean hospital length of stay was 11 +/- 15 days versus 14 +/- 12 days (p = 0.07). Conclusions. The port access approach can be safely adopted for reoperations on the MV without compromising postoperative mortality or MV function. (C) 2015 by The Society of Thoracic Surgeons