The Arteriograph (Tensiomed) is a device that determines aortic pulse wave velocity (PWV) by recording a brachial blood pressure waveform during supra-systolic inflation of a brachial cuff. We validated the working principle of the Arteriograph in a validated 1D computer model of the arterial tree, and found an excellent correlation between Arteriograph (PWV_ATG) and carotid-femoral (PWV_car-fem) PWV (r = 0.98, p<0.01) when homogenously altering stiffness parameters over the complete arterial network. However, selectively altering the stiffness of the aortic or axillo-brachial pathway demonstrated that PWV_ATG is determined solely by axillo-brachial stiffness and not by aortic stiffness. Furthermore, wave intensity analysis shows that the secondary forward compression wave picked up by the Arteriograph and used to assess the travel time of the pressure wave over the aorta is not caused by a reflection from the lower body. Instead, this wave is the result of “trapping” of the initial forward compression wave between the occluding cuff and the axillo-aortic junction. Thus the Arteriograph measures axillo-brachial stiffness, and the good correlation between PWV_ATG and PWV_car-fem is driven by the fact that axillo-brachial and central stiffness were changed to the same extent in the model. Combining these results with earlier findings in literature of good in vivo correlations between PWV_ATG and PWV_car-fem, axillo-brachial and aortic stiffness are likely to be related. However, this does not necessarily imply that axillo-brachial and aortic segments change similarly with age (or disease). We conclude that PWV_ATG is, at best, an indirect and unspecific estimate of aortic stiffness.