BACKGROUND Percutaneous balloon mitral valvuloplasty and durable mitral prostheses have made the role of open mitral commissurotomy (OMC) uncertain. RESULTS Results from the use of St Jude mitral valve replacement (SJMVR) were compared with those of the use of OMC in 312 consecutive patients with mitral stenosis between 1983 and the present. OMC and SJMVR patients were well matched for age, sex, and comorbidity except that SJMVR patients had more severe stenosis and were more likely to undergo concurrent aortic valve replacement. Compared with OMC, SJMVR without chordal preservation involved a longer pump time (158 +/- 81 versus 87 +/- 41 min, P < 0.05), more frequent in-hospital complications or death (57 of 219 [26%] versus 4 of 52 [8%], P < 0.01), and longer hospital stay (13 +/- 11 versus 10 +/- 6 days, P = 0.001). Preservation of chordae to at least 1 mitral valve leaflet decreased early morbidity and mortality rates of SJMVR to values comparable to those of OMC (3 of 41 [7%]). Survival was greater at 10 years for OMC versus SJMVR (86 +/- 5% versus 67 +/- 4%, P = 0.03). Ten-year freedom from cardiac events was not different between groups (49 +/- 9% for OMC versus 55 +/- 4% for SJMVR, P = 0.7). Freedom from subsequent mitral procedures at 10 years was better for SJMVR (96 +/- 2% versus 58 +/- 8%, P < 0.001). CONCLUSIONS In the modern era, SJMVR offers significantly greater durability than does OMC. Chordal preservation at the time of SJMVR may reduce perioperative complications to levels comparable to those of OMC.