Objective: To compare the unobstructed rate and the changes of the diameter of the transplanted vein after the surgery of autogeneic graft of parallel bi-vein and uni-vein with valves.Methods: 24 New Zealand rabbits were randomly divided into experimental group and control group(each group had 12 rabbits).The inferior vena cava(IVC) was replaced by autogeneic graft of parallel bi-vein(in experimental group) or uni-vein(in control group) with valves.The unobstructed rate and the changes of the diameter of the transplanted vein were observed by color Doppler ultrasound 1 d

1 w

2 w and 4 w after surgery.Results: 1d after surgery the diameter of the vessels and the spectrum of the flow returned to normal except one rabbit.At the time of 1 d

1 w and 2 w after surgery

the unobstructed rate of the transplanted vessels in both groups was 100%.There were 1 rabbit in the experimental group and one in the control group

whose transplanted vein were obstructed 4 w after surgery because of the compression of the adhering zone of peritoneum

which was confirmed by anatomy.No thrombus was observed in the transplanted vein in all animals during the 4 weeks after surgery.Conclusion: The transplanted veins are unobstructed during the 4 weeks after autogeneic graft of parallel bi-vein with valves.The unobstructed rate of the transplanted vein in the experimental group and the control group has no significant difference.The diameter of the transplanted vein has no changes in all animals.