Modified human umbilical vein allografts tanned with glutaraldehyde and encased in a polyester mesh were used as arterial substitutes in 13 femoropopliteal reconstructive procedures. A cumulative patency rate of 91% was obtained for the 2 yr follow-up period. Two grafts were lost due to patient death from myocardial infarction. The grafts were determined to be patent at the time of death; no death was in any way associated with the graft material. A graft occluded immediately postoperatively due to the absence of any significant distal runoff to the arteries of the calf. There was no incidence of aneurysmal formation. Based upon previous experience with bovine artery heterograft, the modified human umbilical vein is apparently is apparently superior in this respect. Modified human umbilical vein allograft is superior to autogenous saphenous vein because it is immediately available, valveless, branchless and may be specially constructed as to diameter and length. The allograft is flexible, easy to handle and suture and of sufficient length, elasticity and compliance. Cumulative patency rate for the 2 yr follow-up period compares favorably with that of previously reported uses of autogenous saphenous vein in femoropopliteal arterial reconstruction. The modified human umbilical vein allograft is a good alternative to autogenous saphenous vein in femoropopliteal arterial reconstructive procedures.