In this study we investigated the dependence of the mechanical properties and in particular of the radial compliance of a vascular prosthesis as a function of its usable length. Radial compliance was measured at 60 bpm and in the pressure range 80-120 mmHg. Starting from compliance measurements a simple model was used to calculate the pulse wave velocity and the reflection coefficients between 6 mm and 8 mm grafts (knitted and woven) with iliac and subclavean artery of similar diameter. The results provide an indication of the influence of usable length on the compliance and diameter mismatch at the anasthomosis between graft and host artery.