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 per cent has been obtained for the two year 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, and no death was in any way associated with the graft material. One graft occluded immediately postoperatively due to the absence of any significant distal runoff to the arteries of the calf. There has been no incidence of aneurysmal formation, and based upon our previous experience with bovine artery heterograft, the modified human umbilical vein appears to be superior in this respect. Modified human umbilical vein allograft is superior to autogenous saphenous vein in that it is immediately available, valveless, branchless and may be specially constructed as to diameter and length. We have found the allograft to be flexible, easy to handle and suture, and of sufficient length, elasticity and compliance. Our cumulative patency rate for the two year follow-up period compares favorably with that of previously reported uses of autogenous saphenous vein in femoropopliteal arterial reconstruction. Those results show the modified human umbilical vein allograft to be well deserving as an alternative to autogenous saphenous vein in femoropopliteal arterial reconstructive procedures.