This study evaluates the possible role of the mitral apparatus in left ventricular function after correction of chronic mitral regurgitation. Seventeen patients underwent complete preoperative and early postoperative heart catheterization. Six patients underwent conventional mitral valve replacement (group 1), six mitral valve replacement with preservation of chordae tendineae and papillary muscles (group 2), and five mitral valvuloplasty (group 3). There was no statistically significant difference among the three groups for any hemodynamic parameter as compared before surgery by analysis of variance. After correction of mitral regurgitation the increase in cardiac index was similar for all three groups. Left ventricular end-diastolic volume did not decrease significantly in group 1 (p = NS), but it did in groups 2 and 3 (p less than .005 for both). Left ventricular end-systolic volume increased in group 1 (p less than .025) and decreased in groups 2 and 3 (p less than .01 and .005, respectively). Ejection fraction decreased in group 1 (p less than .005) and did not change in groups 2 or 3 (p = NS). Left ventricular end-diastolic pressure increased in group 1 (p less than .005) and decreased in groups 2 and 3 (p less than .01 for both). These findings suggest that continuity between mitral anulus and left ventricular wall through leaflets, chordae tendineae, and papillary muscles plays a role in left ventricular function after correction of the chronic mitral regurgitation.