This study was performed to evaluate the late results of mitral valve replacement for isolated mitral regurgitation and the early results of mitral valve reconstruction for mitral regurgitation secondary to mitral valve prolapse. Between January 1974 and March 1989, 106 patients underwent isolated mitral valve replacement for mitral regurgitation. There were 54 male and 52 female patients ranging in age at operation from 22 to 76 years (average: 50.2 years). Mitral valve replacement with the Carpentier-Edwards bioprosthesis was performed in 55 patients and with the Björk-Shiley disc valve in 51 patients. The follow-up period ranged from four to 182 months with a mean of 64 months. There were three hospital deaths (2.8%). The actuarial survival including hospital deaths were 94.0% at five years and 89.3% at 10 years. The event-free rate was 75.5% at five years and 51.8% at 10 years. There was no significant differences in these results between two prosthetic valve groups. Because of high incidence of prosthetic valve-related events, mitral valve reconstruction for mitral regurgitation was performed in recent two years. Twenty patients had mitral reconstructive surgery. There were 11 male and nine female patients ranging in age at operation from 22 to 70 years (average: 54.4 years). Two had elongated chordae and 18 had torn chordae (anterior leaflet; four cases, posterior leaflet; 14 cases). There was no hospital and late death. One had reoperation because of severe hemolysis.(ABSTRACT TRUNCATED AT 250 WORDS)