The myxomatous degenerated, prolapsed, or floppy mitral valve is the most common etiology of mitral regurgitation in North American populations. We performed mitral valve reconstruction for this diagnosis in 252 patients from 1984 to 1993. There were 165 males and 87 females ranging in age from 23 to 84 years (mean 64 years); 93 (37%) were > or = 70 years. One hundred eighty-six were New York Heart Association Functional Class III or IV and 29% (72) underwent concomitant coronary bypass operation. Operations included posterior leaflet resection, anterior leaflet resection treatment of chordal pathology by shortening or Gore-Tex replacement, and ring annuloplasty. There were five operative deaths for an operative mortality of 2%. The operative risk in patients under 70 years was 1 of 159 (0.6%) and 4 of 93 (4%) in patients older than 70 years. Ninety percent of patients are asymptomatic in a follow-up period extending 10 years, while structural valve degeneration requiring reoperation at 5 years was 85%. From 1990 to 1993 there has been a less than 5% absolute incidence of structural valve degeneration. Mitral valve reconstruction for complicated floppy mitral valve is feasible and offers excellent early and medium-term results.