In this study, we aimed to evaluate whether hyperpara thyroidism affects the elastic properties of aorta, calculated as aortic distensibility and aortic stiffness index. Eighteen patients with hyperparathyroidism were enrolled in the study. The control group consisted of 18 healthy subjects with similar baseline characteristics. All subjects underwent echocardiographic examination. Internal aortic root diameters were measured at 3 cm above the aortic valve by the use of two-dimensional guided M-mode transthoracic echocardiography, and arterial blood pressure was measured simultaneously from the brachial artery by sphygmomano metry. Two indexes of the aortic elastic properties were measured which are aortic distensibility and aortic stiffness index. The mean aortic stiffness index of hyperparathyroidic patients was higher (3.04 +/- 1.26 vs. 2.36 +/- 1.09; p = 0.048), and aortic distensibility was lower (15.62 +/- 5.84 vs. 22.64 +/- 14.54; p = 0.035) than the control group. The left ventricular (LV) mass index (242.44 +/- 46.3 vs. 212.8 +/- 43.97; p = 0.048), although it has failed to reach statistical significance, and LV wall stress (57.81 +/- 18.22 vs. 46.57 +/- 15.72; p = 0.08) of these patients was also higher than control group. Hyperparathyroidism increases aortic stiffness index and decreases aortic distensibility of primary hyper parathyroidic patients compared with normal population. The affected aortic elastic properties can be a factor in increased LV mass index and wall stress.