Our aim is to describe the clinical experience with stentless mitral valve (SMV) replacement with special focus on the functionality of the SMV. Fifty-two patients (68 ± 8.5 years old; 36 female) have been prospectively evaluated since August 1997. The chordally supported SMV (Quattro) was implanted for mitral stenosis (n = 26), severe incompetence (n = 17), or mixed lesion (n = 9). Preoperative New York Heart Association class was 3.1 ± 0.6. Twenty patients received additional intraoperative ablation therapy. Mean follow-up is 37.3 ± 18.7 months (range, 1 to 65). Surgery was performed using conventional sternotomy (33) or anterolateral minithoracotomy (19). Atrial rhythm was reestablished in 17 of 20 patients. Six patients operated on early in this series required reoperation, 2 for paravalvular leakage, 2 for functional stenosis, 1 with pannus formation due to underlying rheumatoid disease, and 1 for papillary flap rupture after 5.1 years. Mortality was 1 perioperative (1.9%, nonvalve related) and 1 after reoperation due to multiorgan failure. During late follow-up (30 ± 7 months postoperatively) 5 patients died of noncardiac causes. Regular echocardiographic control revealed good SMV function (maximum transmitral blood flow velocity 1.7 ± 0.2 m/s; mean transmitral pressure gradient 3.9 ± 1.2 mm Hg) and well-preserved ejection fraction postoperatively as well as at most recent follow-up. The clinical experience after 5.5 years of SMV implantation is promising. Preservation of annuloventricular continuity is advantageous. However, long-term durability remains to be proved.