Background: Metabolic syndrome predisposes to left ventricular dysfunction and heart failure, early detection of associated subclinical cardiac changes has important diagnostic and prognostic values. 2D strain and strain rate allow detection of subtle abnormalities of global and regional left ventricular systolic and diastolic functions. Objectives: To detect early diastolic dysfunction in the left ventricle in patients with metabolic syndrome by 2D speckle tracking echocardiography based on global longitudinal isovolumic relaxation strain rate. Subjects and Methods: This prospective study included a total of 100 subjects divided in to 75 metabolic syndrome (MS) patients referred to Al-Azhar university hospital outpatient clinic for evaluation and treatment of hypertension and/or diabetes mellitus and 25 age and sex matched healthy volunteers as a control group. All subjects underwent conventional echocardiographic examination and assessment of diastolic dysfunction by speckle tracking. Results: There were no statistically significant differences between MS and controls in all traditional parameters of LV systolic function. On the other hand, significant differences were observed between MS and the control group in most of the parameters of GLS and SR IVR. Conclusion: Impairment of diastolic function detected by speckle tracking based on global longitudinal isovolumic relaxation strain rate in metabolic syndrome patients.