Background: Differentiation between types of left ventricular hypertrophy (LVH) whether physiological or pathological is essential for Management and/or follow up. Purpose: To examine the accuracy of 2D and 3D strain and LV dyssynchrony for differentiating athletes with moderate LVH (13—15 mm) from patients with hypertrophic cardiomyopathy (HCM). Patients & Methods: A prospective case control study carried out at Benha University Hospitals, Cardiology Department and National Heart Institute during the period from March 2019 to September 2020.The study included 100 subjects divided into four groups:First Group: 25 competitive athletes with moderate LVH (13—15 mm),Second Group: 25 competitive athletes without LVH, Third Group: 25 patients with HCM and moderate LVH (13—15 mm), andFourth Group: 25 sedentary healthy subjects (control group). Results: Our result reported thatthere is a significant difference between athletes with LVH and HCM group regarding 2D & 3D GLS, GRS and GAS (where these measures were higher in athletes with LVH). Also, there is a significant difference between Athletes without LVH and HCM group GRS and GAS (where these measures were higher in athletes without LVH) while no significant difference between groups regarding GCS. Also, LV end-diastolic diameter has the highest sensitivity (98%) with cutoff < 54 mm for distinguishing HCM from athletes with or without moderate LVH with high significance (p < 0.001). Conclusion: We demonstrated that a preserved 2D and 3D longitudinal strain function and the absence of LV dyssynchrony can be used to exclude HCM, while abnormal longitudinal function associated with dyssynchrony is specific to HCM.