Abstract To look for a substitute material of microvessel, 30 rabbits were divided into 2 groups. A segment of 5mm of rabbit femoral artery was resected and a segment of 10mm of human placental artery was placed in the defect with both ends anastomosed. Twenty experimental rabbits received freezedried human placental vessel and 10 rabbits received fresh as control. After 24 hours, 2 weeks, 3 months, the arteries were explored. If the artery was found to be obstructed, the segment was removed for histologic examination. The results showed: in the experimental group, 2 weeks after operation, the rateof patency was 85%, and it decreased to 50% 3 months after the operation. Under the light and scanning electronic microscope, the transplanted vessels were decomposed and inside the unobstructed transplanted vessels in both groups a layer of fibrous tissue was formed as the new wall of vessel. It was concluded thatthe immunologic reaction could not be prevented but would only be put off for aperiod of time by cryochem. Further more study should be done in using placental atery as a substitute material in repairing vascular defect.