One hundred and fifty-five patients with isolated mitral regurgitation were referred from our Department of Cardiology for mitral valve repair between 1972 and 1990. Men were in the majority (59%), the mean age was 51 years and 61% of the patients were in NYHA class III or IV. Degenerative or dystrophic etiologies predominated, followed by rheumatic origins (17%) and bacterial endocarditis (14%). Surgical repair was performed using Carpentier's techniques: insertion of a prosthetic ring (87%) valvular resection (73%), valvular mobilization (11%), closure of a perforation (4,5%) and resection of vegetations (4,5%). Two patients died during surgery and 7 were lost to follow-up; the others were followed for an average of 4 years, i.e., a cumulative follow-up of 584 years/patients. The overall results at 11.5 years were satisfactory: 84.5% survival rate and 64.5% with good valvular function. The linearized rates of endocarditis, thromboemboli, hemorrhagic complications (51 patients were taking anticoagulants) and repeated interventions were, respectively: 0.35, 1.54, 0.17 and 2.05%/patient-year. Residual mitral regurgitation was sought by clinical and Doppler examinations: 55.5% of the patients had none, 26% had mild, 10.3% had moderate and 8.2% had severe regurgitation. Analysis of the latter two groups identified 3 influencing factors: rheumatic origin of the regurgitation, surgery on the anterior cusp and the year surgery was performed (the post-surgical incidence has decreased in recent years). Other, less-well-known complications were also found: left ventricular outflow tract obstruction, progressive evolution towards mitral stenosis, development of aortic regurgitation (usually discreet) and formation of left atrial thrombi.(ABSTRACT TRUNCATED AT 250 WORDS)