Background We were to determine that whether the hypertensives with diabetes mellitus (DM) have more increased ventricular-arterial stiffness and more decreased diastolic function than the patients without DM measured by noninvasive method using echocardiography. Methods Having normal left ventricular (LV) ejection fraction, the hypertensives without DM (group 1, n=200), the hypertensives with DM (group 2, n=60), and age-, and sex-matched controls (n=20) were enrolled. Echocardiography was performed including LV wall thickness, dimension, and Doppler imaging including transmitral early filling velocity (E), mitral annular early diastolic velocity (E���), and time velocity integral of LV outflow tract flow to calculate stroke volume (SV) and end-diastolic elastance (Ed= E/E��� divided by SV). Blood pressure(BP) was measured on supine position before and after echocardiographic examination. Results The hypertensives with or without DM had higher body mass index, BP, and LV mass than the controls. Group 2 had more increased Ed (0.17짹0.05 vs 0.13짹0.03, p=0.01) than the controls, had more depressed arterial compliance (SV divided by pulse pressure) (1.51짹0.42 vs 1.69짹0.52, p<0.05) than group 1. There was no difference in LV function between the hypertensives with and those without DM. Conclusions The hypertensives with DM had more increased ventricular-arterial stiffness than the hypertensives without DM, but diastolic function was not different. DM seems to have additive adverse effects on the ventricular-arterial stiffening in the hypertensives.