Sixty-two patients with rheumatic mitral valve disease (mean age 42.2 +/- 10.2 years) underwent repair of chordae tendineae between June 1974 and May 1994. Chordal shortening was done in 38 patients, fenestration in 17, resection of secondary chordae in 3, replacement in 2, and transposition in 2. In 41 patients, mitral commissurotomy was also done. Ring annuloplasty was done in all patients. The mean follow-up was 10.2 years (range 2 months to 20 years). The completeness of follow-up during the closing interval (January to July 1994) was 100%. Hospital mortality occurred in four patients (6.5%) and nine patients died during the late follow-up. The actuarial survival curve at 20 years was 65.8% +/- 10%. Six patients with mitral valve dysfunction (restenosis 4, insufficiency 2) and one with aortic valve dysfunction (structural deterioration of bioprosthesis) underwent reoperation. The actuarial curve of freedom from reoperation at 20 years for mitral valve dysfunction was 73.1% +/- 10.5%. In the 49 surviving patients, a Doppler echographic study during the closing interval showed a mean mitral valve area of 1.9 +/- 0.3 cm2. In the 43 patients with a repaired native valve, absent or trivial mitral regurgitation was documented in 35 and mild or moderate regurgitation in 8. In conclusion, repair of chordae tendineae in rheumatic mitral valve disease when feasible is a stable and safe procedure with a low prevalence of reoperation. However, the type of reconstructive operation and experience of the surgical team are major considerations in successful repair of the mitral valve.