Carrying out a mitral valve replacement (MVR) while preserving all chordae tendineae in patients with mitral regurgitation has been proven beneficial to the left ventricular performance. To evaluate the effectiveness of this technique in patients with mitral stenosis, a comparison of the echocardiographic data between patients who were operated on using this technique (Group Preservation=Group^P, n=15), and those operated on using the conventional method of MVR (Group Conventional=Group^C, n=15) was made. All patients were examined before surgery, 6 months after surgery and 8 years after surgery. The study population was limited to patients who had no evidence of coronary artery disease, aortic stenosis and-/or regurgitation and patients who had pure mitral stenosis. Echocardiographic measurements obtained both 6 months and 8 years postoperatively revealed a significant decrease in the left ventricular ejection fraction in Group^C (61.33±9.29% preoperatively, 53.2±10.3% postoperatively). The difference between the decrease in the left ventricular ejection fraction of the two groups was statistically significant (−0.71±6.28% in Group^P, −8.07±13.35% in Group^C). There was no evidence of prosthetic valve dysfunction and no operative deaths. Two patients died in Group^P, 3 patients died in Group^C within the 8 year period. The conclusion was reached, that if suitable, mitral valve replacement while preserving the chordae tendineae is expected to have a beneficial effect on postoperative left ventricular performance in patients with mitral stenosis.