Aims & Objectives–MAPSE DERIVED EJECTION FRACTION CAN BE USED AS AN ALTERNATIVE TO THE CONVENTIONAL ECHOCARDIORAPHIC MEASUREMENTS OF EJECION FRACTION IN EVERY DAY CLINICAL PRACTICE WITH PATIENTS WITH LV SYSTOLIC DYSFUNTION & VALIDATION OF MITRAL ANNULAR PLANE SYSTOLIC EXCURSION DERIVED FORMULA TO CALCULATE THE EJECTION FRACTION IN PATIENTS WITH LV SYSTOLIC DYSFUNCTION EF=4.8XMAPSE(mm)+5.8 in adult male &4.2X MAPSE(mm)+20 in adult female Material and Method–Our study is observational, prospective study with cross sectional data collection done in a period of nov 2018 to nov 2019, The study included 151 adult male and female patients with LV systolic dysfunction fulfilling all inclusion criteria, LVEF measured by average MAPSE and LVEF measured by visual inspection, M–mode, and modified Simpson’s rule was statistically correlated to know the validity of MAPSE derived ejection in case of LV systolic dysfunction. Result– The current study showed a significant positive correlation between average MAPSE and EF measured by M–mode (r =0.980, P < 0.001), EF measured by Simpson’s rule (r =0.968, P < 0.001), and EF measured by visual inspection(r =0.960, P < 0.001). The mean differences in the EF derived by MAPSE formula between the inter–observer was(–0.14 ± 3.18 ). Conclusion– MAPSE–derived EF using the equation EF = 4.8 × MAPSE (mm) + 5.8 for male and EF = 4.2×MAPSE (mm)+20 for female ,is a valid echocardiographic parameter in adult males and females with impaired LV systolic function to asses global LV longitudinal function with minimal interobserver variability