From 1969 to 1985, mitral valve repairs using Carpentier's technique were performed for acquired mitral valve incompetence. 72 patients required a reoperation 3 days to 13 years later (mean 5 +/- 3.5 years). The reoperation rate risk was dependent upon the etiology: Barlow 0.6 +/- 0.2% patient year, fibro-elastic deficiency 0.7 +/- 0.3, endocarditis 1.7% Rheumatic disease 4.6 +/- 1.4%. The risk of reoperation in Rheumatic disease is significantly higher (p less than 0.05) than in degenerative disease. The causes of failures could be categorized into two groups according to whether they are surgeon related or valve related: Group I, Prosthetic ring dehiscence or malposition 15%, anulus dilatation (when no ring was implanted) 4%, triangular resection of the anterior leaflet 4% residual prolapse 8.3%. Group II, Recurrent prolapse 16.6% valve stenosis 17%, leaflet retraction 35%. Failures in Group I can be reduced with "increased" experience as opposed to group II. At reoperation valve repair was possible in 15.3% of the cases whereas valve replacement was necessary in 84.7% with an overall operative mortality of 1.4%. We conclude that mitral valve repair in acquired mitral incompetence carries out a small risk of reoperation. Most of the repair failures are surgeon related in degenerative disease and valve related in rheumatic disease.