Background : Left ventricular (LV) ejection fraction (LVEF) is mostly used as a parameter of systolic function which is often assessed without considering changes in ventricular structure, geometry and hypertrophy. LV global function index (LVGFI) is a novel parameter that integrates LV structure with global function in the assessment of LV cardiac performance. Our study aimed to throw light on LVGFI as a diagnostic marker of early subclinical contractile dysfunction in patients with concentric Left ventricular hypertrophy.Methods: A case-control study involving 123 participants; they were divided into three groups, control (Group 1) 41 volunteers, LVH without systolic dysfunction (Group 2) 41 cases, and LVH with systolic dysfunction (Group 3). Conventional systolic function assessment, LVGFI was expressed by the equation;(LV stroke volume / LV global volume) *100 and tissue doppler mitral annulus Sa wave, IVCT Isovolumetric contraction time.Results: (LVGFI), and Sa mitral annulus had the lowest mean value in G3. LVGFI had a positive correlation with average Sa (r=0.755, p <0.001), EF (m-mode, r = 0.235, p=0.008) and EF (Simpson, r = 0.305, p=0.001). Multivariate analysis showed that LVGFI had the best relationship with Sa average (p=0.001), EF Simpson (p= 0.002) and then hypertension(p=0.02*). LVGFI had an area under the curve of 0.74, sensitivity of 85%, specificity of 80%, and cutoff of less than 22.4% for subclinical LV systolic dysfunction. Conclusion: LVGFI at a cut-off of less than 22.4% was useful in detecting subclinical LV systolic dysfunction in