Objective: Mitral valve stenosis (MS) remains as an important cause of morbidity despite evolution in diagnosis and treatment. Generally, left ventricular (LV) systolic functions are well preserved in patients with MS. However, there are some studies showing impaired LV systolic functions in patients with pure MS. The purpose of this study was to evaluate subclinical LV systolic dysfunction in a cohort of isolated mild-to-moderate MS patients with normal LV ejection fraction (EF) by using tissue Doppler imaging (TDI) and velocity vector imaging (VVI) techniques. Methods: Fifty patients with isolated mild-to-moderate MS (84% female, mean age 49.1±10.0 years) and 60 healthy subjects (76.7% female, mean age 49.1±10.5) were included in this cross-sectional observational study. Conventional echocardiography, TDI, strain (S) and strain rate (SRs) analysis were performed in all patients. Results: Transmitral mean pressure gradient was 6.4±3.0 mmHg and mean mitral valve area was 1.45±0.36 cm2 in patients with MS. Both longitudinal and circumferential S and SRs were significantly reduced in patients with MS (p<0.001). TDI-derived parameters myocardial acceleration during isovolumic contraction (IVA) and peak velocity during systolic ejection (Sa) were also significantly decreased in patients with isolated MS (p<0.001). LV ejection fraction (EF) was not correlated with deformation indices. Deformation parameters were not correlated with transmitral gradient or mitral valve area. Conclusion: VVI-derived deformation parameters may identify subclinical systolic dysfunction in patients with isolated MS with normal EF. These findings may give way to optimal timing for mitral valve surgery.