Arterial stiffness is a strong determinant of cardiovascular risk. Pulse wave velocity (PWV) and the augmentation index (AIx) are widely used as arterial stiffness indices. We studied the reproducibility of these indices and their association with cardiovascular risk factors in hypertensives. We measured brachial blood pressure (BP), brachial-ankle PWV (baPWV) and carotid AIx (cAIx) twice (at the baseline and 4 weeks after the baseline) using an automatic device in 103 hypertensives. The mean intraobserver-intersession difference was 29.0 cm/s with an SD of 201.6 cm/s for baPWV, and 0.5% with an SD of 5.9% for cAIx, and the Bland-Altman plots demonstrated the good reproducibility of baPWV and cAIx. Both baPWV and cAIx (the average of the 1st and the 2nd measurements) were significantly correlated with age, systolic BP (SBP), and pulse pressure (all, p <0.005); however, these factors were not correlated with each other (r =0.06, NS). cAIx was correlated with height, heart rate (HR), total cholesterol, and low density lipoprotein cholesterol (LDL-C) (all, p <0.05). In multiple regression analysis, age, SBP, and HR emerged as significant independent predictors of baPWV (adjusted R²=0.43, p <0.0001), while height, SBP, HR, and LDL-C emerged as significant independent predictors of cAIx (adjusted R²=0.58, p <0.0001). Both PWV and AIx measured using an automatic device were fairly reproducible, and their associated risk factors appeared to be different. Automated simultaneous measurement of these arterial stiffness indices may be useful for risk stratification of hypertensives. (Hypertens Res 2004; 27: 851-857)