Osteoporosis has been associated with cardiovascular disease. We found increased augmentation index, a measure of wave reflections and arterial stiffness, and central pressures in osteoporotic postmenopausal women. They also showed a higher estimated aortic pulse wave velocity, indicating a stiffer aorta. These changes may increase cardiovascular risk in postmenopausal osteoporosis. Introduction Evidence suggests a link between osteoporosis and cardiovascular disease. We investigated whether augmentation index (AIx), a measure of pulse wave reflections and arterial stiffness, is increased and related to the osteoprotegerin (OPG)/receptor activator of nuclear factor-kappa B ligand (RANKL) system in postmenopausal osteoporosis. Methods AIx and central aortic haemodynamics were assessed using pulse wave analysis in 182 cardiovascular disease-free osteoporotic postmenopausal women and in 160 controls. Statistical analysis was performed by unpaired t test, Mann-Whitney test, Spearman's correlation coefficient, and multivariate linear regression analysis. Results AIx (37.2 +/- 7.0 vs. 29.6 +/- 9.2 %, P < 0.0001) and central aortic systolic (117.5 +/- 12.1 vs. 111.4 +/- 12.2 mmHg, P < 0.0001) and pulse (40.5 +/- 10.3 vs. 36.4 +/- 8.1 mmHg, P = 0.0007) pressures were significantly higher in osteoporotic patients than in controls. The estimated aortic pulse wave velocity (PWV) was also significantly higher in the osteoporotic group. In multivariate analysis for osteoporotic patients, femoral neck and lumbar spine bone mineral density T scores were independent negative predictors of AIx (P < 0.0001). AIx was not correlated with serum levels of OPG and RANKL. Conclusions Osteoporotic postmenopausal women show increased AIx and central aortic pressures, and a higher estimated aortic PWV, indicating a stiffer aorta. Such alterations may increase cardiovascular risk in postmenopausal osteoporosis.