['Double valve replacement has been advocated for patients with combined aortic and mitral valve disease. This study investigated the alternative that, when feasible, mitral valve repair with aortic valve replacement is superior.', 'From 1975 to 1998, 813 patients underwent aortic valve replacement with either mitral valve replacement (n = 518) or mitral valve repair (n = 295). Mitral valve disease was rheumatic in 71% and degenerative in 20%. Mitral valve replacement was more common in patients with severe mitral stenosis (P =.0009), atrial fibrillation (P =.0006), and in patients receiving a mechanical aortic prosthesis (P =.0002). These differences were used for propensity-matched multivariable comparisons. Follow-up extended reliably to 16 years, mean 6.9 +/- 5.9 years.', 'Hospital mortality rate was 5.4% for mitral valve repair and 7.0% for replacement (P =.4). Survivals at 5, 10, and 15 years were 79%, 63%, and 46%, respectively, after mitral valve repair versus 72%, 52%, and 34%, respectively, after replacement (P =.01). Late survival was increased by mitral valve repair rather than replacement (P =.03) in all subsets of patients, including those with severe mitral valve stenosis. After repair of nonrheumatic mitral valves, 5-, 10-, and 15-year freedom from valve replacement was 91%, 88%, and 86%, respectively; in contrast, after repair of rheumatic valves, it was 97%, 89%, and 75% at these intervals.'] Is mitral valve repair with aortic valve replacement superior to double valve replacement?