From January 1988 to December 1995, 27 patients, 11 men and 16 women, underwent surgical intervention at our institution for prosthetic valve dysfunctions. The mean age was 43.5$pm$12.2 years. Seventeen(63.0%) patients had the mitral valve replacement, 8(29.6%) the aortic valve, 1(3.7%) the aortic composite graft, and 1(3.7%) the tricuspid valve. Mean follow-up period was 49.5$pm$30.9 months. In 12 bioprostheses, mean interval between the previous valve replacement and the reoperation was 104.9$pm$34.9 months. The causes of redo surgery were structural deterioration of the prosthetic valve (12/12, 100%), paravalvular leak (2/12, 16.7%), and prosthetic valve endocarditis(1/12, 8.3%). In 15 mechanical prostheses, the mean interval was 55.2$pm$43.7 months. The causes of redo surgery were pannus formation (8/15, 53.3%), paravalvular leak(4/15, 26.7%), and valve thrombosis(3/15, 20.0%). Posto- perative complications occurred in 7 patients (25.9%). There was no intraoperative death. But one patient, who received mechanical aortic valve replacement died on the 3rd postoperative day due to low cardiac output and multiorgan failure.