Transplantation of femoral vein grafts was performed on 33 mongrel dogs to assess graft patency and valvular function after storage in glutaraldehyde. The grafts were removed from the donor, flushed with room temperature heparinized lactated Ringer's solution, and then stored in a 0.2% glutaraldehyde solution for 16 hr. At the time of grafting, the veins were again flushed with lactated Ringer's and anastomosed orthotopically to the recipient. An arteriovenous fistula was also created. Postoperatively the animals received daily doses of aspirin (2 mg/kg) and dipyridamol (50 mg). The following groups were studied: Group I (n = 10) served as controls and received fresh autografts. Group II (n = 13) received autografts stored for 16 hr in 0.2% glutaraldehyde. Group III (n = 10) received allografts stored similarly in glutaraldehyde for 16 hr. The grafts were monitored for evidence of patency. All grafts were removed for histological evaluation when patency was no longer detected or at the end of 7 weeks. Of the fresh and glutaraldehyde-preserved autografts (Group 1), 100% were patent at 7 weeks, and generally retained valve function. Patency of allografts was only slightly inferior but valve function was disappointingly poor at 7 weeks.