Aim: Idiopathic mitral valve prolapsus (MVP) is characterized by myxomatous degeneration of mitral valve. The most common determinant of cardiovascular mortality in patients with MVP is left ventricular (LV) dysfunction. Therefore we aimed to evaluate LV functions of cases with isolated MVP by tissue Doppler echocardiography (TDE). Method: Twenty five patients with MVP (mean age, 31±12 years) were enrolled the study as MVP group. Control group was consisted 20 age and sex matched patients (mean age, 34±9 years) were enrolled to this study. LV functions were detected by using conventional echocardiography and TDE. Myocardial peak systolic (Sm), early (Em) and late (Am) diastolic filling velocities, Em/Am, isovolumetric contraction time (ICT), isovolumetric relaxation time (IRT) and ejection time (ET) were obtained in the basal segments of the inferior-septal and lateral wall. Myocardial performance index (MPI) was calculated. Result: Mild degree mitral regurgitation was present in 10 (40%) of patients with MVP, and moderate degree mitral regurgitation was present in 2 (8%) of patients. No difference was found between the two groups with regard to diastolic parameters. TDE-derivated MPI values were similar in all segments in two groups. There was significant difference between the two groups with regard to LV mean Sm and lateral wall Sm (11.6±2.8 vs. 9.4±1.0, p=0.001; 13.0±3.9 vs. 9.2±2.3, p=0.001 respectively). Conclusion: Isolated MVP without significant mitral regurgitation does not affect LV diastolic functions and MPI. However, Sm of late ral wall and LV mean was higher in patients with MVP than patients without MVP.