In the authors' centers, fresh saphenous veins (FSV) procured from routine saphenectomies have been preferred to synthetic prostheses in cases of difficult vascular accesses (VA) for dialysis. The need for veins of different lengths and diameters prompted them to preserve SV by instantaneous freezing in liquid nitrogen since November 1987. Until now, 59 patients have received 35 FSV and 32 cryopreserved SV (CSV). Actuarial patency rates after 1 year are 82% and 72%, respectively. The 6-keto prostaglandin F1 alpha measured on punches of both veins showed residual production of prostacyclin even in CSV, but this was unresponsive to stimulation by arachidonic acid and bradykinin, or to inhibition by aspirin. In the authors' opinion, despite marked endothelial damage, satisfactory clinical results can be obtained by this very simple and cheap method of storing biologic prostheses for dialysis VA.