The Seventh Report of the Joint National Committee on the Prevention, Detection, Evaluation, and Treatment of High Blood Pressure classifies blood pressure (BP) as normal, prehypertension, and hypertension. Although it has been shown that there is a relationship between hypertension and arterial stiffness, there is not sufficient data about arterial stiffness in patients with prehypertension. The present study was designed to evaluate arterial stiffness and wave reflections in subjects with prehypertension. We evaluated arterial stiffness and wave reflections of 45 subjects with prehypertension and an age-matched control group of 40 normotensive individuals, using applanation tonometry (Sphygmocor, AtCor Medical, Sydney, Australia). Aortic pulse wave velocity (PWV) was measured as indices of elastic-type aortic stiffness. The heart rate-corrected augmentation index (AIx@75) was estimated as a composite marker of wave reflections and arterial stiffness. Aortic PWV (10 +/- 2.5 vs. 8.6 +/- 1.7, m/s, p = 0.004) and AIx@75 (21 +/- 8.3 vs. 10 +/- 9.1, %, p = 0.0001) were significantly higher in subjects with prehypertension than in the control group. In multiple linear regression analysis, we found that the presence of the prehypertension was a significant predictor of aortic PWV (beta = 0.26, p = 0.009) and AIx@75 (beta = 0.46, p = 0.0001). Our results suggest that arterial functions were impaired even at the prehypertensive stage.