The stiffness of the aorta can be determined by measuring carotid–femoral pulse wave velocity (PWV cf ). PWV may also influence the contour of the peripheral pulse, suggesting that contour analysis might be used to assess large artery stiffness. An index of large artery stiffness (SI DVP ) derived from the digital volume pulse (DVP) measured by transmission of IR light (photoplethysmography) was examined. SI DVP was obtained from subject height and from the time delay between direct and reflected waves in the DVP. The timing of these components of the DVP is determined by PWV in the aorta and large arteries. SI DVP was, therefore, expected to provide a measure of stiffness similar to PWV. SI DVP was compared with PWV cf obtained by applanation tonometry in 87 asymptomatic subjects (21–68 years; 29 women). The reproducibility of SI DVP and PWV cf and the response of SI DVP to glyceryl trinitrate were assessed in subsets of subjects. The mean within-subject coefficient of variation of SI DVP , for measurements at weekly intervals, was 9.6%. SI DVP was correlated with PWV cf ( r = 0.65, P <0.0001). SI DVP and PWV cf were each independently correlated with age and mean arterial blood pressure (MAP) with similar regression coefficients: SI DVP = 0.63+0.086×age+0.042×MAP ( r = 0.69, P <0.0001); PWV cf = 0.76+0.080×age+0.053×MAP ( r = 0.71, P <0.0001). Administration of glyceryl trinitrate (3, 30 and 300 μ g/min intravenous; each dose for 15 min) in nine healthy men produced similar changes in SI DVP and PWV cf . Thus contour analysis of the DVP provides a simple, reproducible, non-invasive measure of large artery stiffness.