Between 1968 and 1990, 68 patients (33 male, 35 female) with a mean age of 47 years were subjected to reoperation (62 valve replacements, 6 reconstructions) after primary mitral valve reconstruction (mean interval = 81 months). The indication for reoperation was residual valve insufficiency in 51, and stenosis in 17 patients. The average preoperative New York Heart Association (NYHA) class was 3.0. The average follow-up was 63 months. The operative mortality was 8.8% (8 out of 68 patients). The actuarial late survival was 90% after 5, and 73% after 8 years. After a second mitral valve reconstruction 66% (four out of six patients) died (one early, three late). The incidence of second reoperations was 4.4% (3 out of 68 patients), and of thromboembolic complications 11.8% (8 out of 68 patients). The mean NHYHA class improved significantly. The actuarial freedom from second reoperations was 98% and 90%, and from thromboembolic complications 91% and 82% after 5 and 10 years, respectively. Endocarditis did not occur, whereas two patients on Coumadin anticoagulation had non-fatal gastrointestinal bleeding. Late survival was less favorable (P < 0.05) in patients operated on before 1980, in a higher preoperative NYHA class, after a second valve reconstruction, and if pulmonary hypertension or atrial fibrillation was present. Significant independent risk factors were older age and earlier reoperation, pulmonary hypertension or higher NYHA class postoperatively. For the last to years it has been possible to perform reoperations after mitral valve reconstructions with good early and excellent late results. The mortality and complication rates were similar to those for primary mitral valve reconstructions.(ABSTRACT TRUNCATED AT 250 WORDS)