Objective: In this study we evaluated the elastic properties of the aorta in patients with subclinical hypothyroidism and their relation with left ventricular diastolic function by transthoracic echocardiography.Patients and Methods: Aortic transthoracic echocardiography was performed and the aortic elasticity was evaluated using the following parameters; strain, the beta index and distensibility.results: There was significant difference in terms of aortic strain (5.79% vs. 9.45% p <0.001) and distensibility (4.64 versus 3.02 10-3.cm2. dyn-1. p <0.005) between the control group and patients with subclinical hypothyroidism group. In the subclinical hypothyroidism group the average mitral early diastolic velocity (E). (p <0.05) were significantly lower than the mean mitral diastolic flow velocity / mitral late diastolic flow velocity (E / A) (p <0.01) observed in the control group. and higher than the mean mitral late diastolic flow velocity (A) and isovolumetric relaxation time (IVRT) (P <0.05) in the control group.conclusions: In patients with subclinical hypothyroidism an increase in the aortic stiffness was observed. The diastolic dysfunction observed in subclinical hypothyroidism is mainly responsible for the increase in the aortic stiffness.