Low androgen levels in men are associated with increased cardiovascular risk, through unclear mechanisms. We measured arterial stiffness ('compliance') in 21 men receiving complete testosterone suppression therapy for prostate cancer, and in 25 controls. Systemic arterial compliance (SAC), which assesses proximal aortic stiffness, was calculated by simultaneous recording of aortic flow and carotid artery pressure (the 'area method'). Aorto-femoral (A-F), aorto-radial (A-R) and femoral-dorsalis pedis (F-DP) pulse-wave velocities (PWVs) were recorded using the 'Complior' system. SAC was significantly lower in the androgen-depleted men compared to controls (0.81 ± 0.53 vs. 1.18 ± 0.43 arbitrary compliance units, p = 0.01, mean ± SD). Correspondingly, their A-F PWV was higher (14.1 (10.1-21.8) vs. 12.4 (9.6-17.4) m/s, p = 0.03, median (range)). Cases tended to be older (75 ± 7 vs. 71 ± 6 years, p = 0.07), and to have higher systolic blood pressure (148 ± 22 vs. 143 ± 17 mmHg, p = 0.40); however, SAC was still significantly lower (p = 0.03) after adjustment for age and stratification for central systolic pressure (= or > the median). Adjustment of A-F PWV for age and central systolic pressure reduced significance to p = 0.07. There was no significant difference in peripheral PWVs between groups. In conclusion, testosterone suppression is associated with increased aortic stiffness, only partly explained by age and blood pressure. Loss of androgens in men might therefore adversely affect cardiovascular risk.