Total obstruction, stenosis, or ligation of any large vein is associated with significant morbidity. No synthetic grafts can adequately replace large veins, particularly in areas subjected to motion (flexion or extension). Artificial prosthetic materials usually occlude within a short period. Since 1987, the author has used cryopreserved allografts of small aortas varying from 1 to 1.7 cm in diameter to replace large vein channels in the upper or lower body. These allografts provide a manageable, pliable conduit with normal endothelium. He implanted grafts bridging gaps from 4 to 30 cm in length, in 14 patients (10 women, 4 men). Veins replaced were five iliac, three iliofemoral, and six subclavian-innominate. The long-term patency rate (follow-up 3 months to 10 years) is 93%. The use of small aortic cryopreserved homografts for large vein replacement, particularly in mobile areas (groin, thoracic inlet, pelvis) is recommended. These grafts appear superior to any previous grafts used for the same purpose.