We investigated whether there was a correlation between the simultaneous assessments of augmentation index (AI) and pulse wave velocity (PWV), undertaken by the SphygmoCor system, and what were the principal factors responsible for differences in these two putative assessments of arterial stiffness, in 105 offspring (41 men, 64 women) aged 19-71 years, of patients with familial hypertension. Arterial stiffness was measured using the SphygmoCor pulse wave analysis system. AI and PWV correlated significantly and positively (r = 0.29, p < 0.005) and the strength of the correlation was greater when each gender was examined separately. This led us to observe several-fold higher AI in women (22.04 +/- 12) than in men (8.59 +/- 13) (p < 0.001); the difference could be explained only in part by an inverse regression correlation between AI and height (r = -0.45; p < 0.001), but not PWV. AI was also more influenced than PWV by heart rate and blood pressure. AI is strongly correlated with a previously validated estimate of arterial stiffness, PWV. It is probable that separate normal ranges should be established for men and women, while further studies determine what parameters other than height are responsible for the gender difference.