Background Surgical series on mitral valve reoperation are limited by small numbers and lack of national representation. Large-scale outcomes of reoperation for mitral valve surgery remain uncertain. Methods This is a descriptive analysis of 1,627 Medicare beneficiaries who underwent mitral valve reoperation within a 3-year follow-up period after an initial mitral operation (repair or replacement) that took place between 2000 and 2006. The primary outcomes were hospital mortality and long-term survival. Results The 1,627 patients included in the study comprise 1.6% of patients who underwent operation between 2000 and 2006. The initial surgery was repair in 49.9%, bioprosthetic replacement in 22.0%, and mechanical replacement in 28.1%. Re-repair was performed in 15.4%. Hospital mortality was 12.0% and was similar for repair and bioprosthetic or mechanical replacement. Reoperative mortality was similar for men and women and for patients aged 75 years or less versus more than 75 years; and was significantly higher for nonelective than for elective operations (15.6% versus 5.5%, p = 0.0001), for patients with endocarditis than without endocarditis (21.4% versus 11.0%, p = 0.0001), and for patients with heart failure than without heart failure (14.2% versus 9.9%, p = 0.0080). Cumulative long-term survival rates were 58.6% at 5 years. Conclusions The incidence of mitral valve reoperation within 3 years after initial repair or replacement is low but carries high surgical risk, which is significantly increased by certain preoperative characteristics, such as urgent status, endocarditis, and heart failure.