OBJECTIVE: To evaluate aortic function and its relation to left ventricular diastolic function in patients with hypertension, diabetes, or both, without coronary artery disease. METHODS: Study groups were composed of 27 healthy participants and 25 patients with hypertension, 24 with diabetes, and 18 with hypertension and diabetes. Coronary artery disease was excluded in all of the study participants. Aortic strain and distensibility were calculated from the aortic diameters measured by echocardiography and blood pressure obtained by sphygmomanometry. RESULTS: There were significant differences between the control and the patient groups (hypertensive, diabetic, and diabetic-hypertensive) in aortic strain (mean (SD) 18 (8)% v 11 (7)%, 9 (3)%, and 8 (3)%, respectively, p < 0.001) and distensibility (10 (5.1) v 3.1 (1.5), 5.1 (2.8), and 2 (0.9) cm2/dyn/10(3), respectively, p < 0.001). In a multivariate analysis, the parameter most closely related to the deceleration time in the control group was aortic distensibility (standardised beta coefficient -0.50, p = 0.002, overall R2 = 0.25). In the patient group, the parameter most closely related to deceleration time was also aortic distensibility (standardised beta coefficient -0.36, p = 0.009, overall R2 = 0.13). Even though the study group variable was entered in to the multivariate model, aortic distensibility was found to be the parameter most closely related to deceleration time (standardised beta coefficient -0.48, p < 0.001, overall R2 = 0.22). CONCLUSION: Aortic stiffness is increased in patients with hypertension, diabetes, or both even after the exclusion of coronary artery disease. Aortic stiffness and left ventricular diastolic dysfunction are also associated in these patients.