In order to investigate the effect of vascular beds on the vascular wall of autogenously grafted vein, femoral veins were reversely placed in between the cut ends of collateral femoral arteries in 11 dogs with atraumatic technique. The grafted veins were covered with vivid muscle or skin respectively after being assured to be patent, and investigated by histomorphologic method and computerized image analysis technique at postoperative intervals of 1 week, 4 weeks and 16 weeks. The results showed that: 1. One graft developed pseudoaneurysm at 1 week, and two grafts were occulded in skin-covered group, whereas, no complications occurred in muscle-covered group. 2. Intimal thickening of grafts in skin-covered group was much more obvious than that in the muscle-covered group (P lt; 0.05). 3. The relative contents of microstructural components of the graft wall showed no significant difference quantitatively between the two groups. So, the conclusion was: 1. Subcutaneous transplantation appeared to be a potential causative factor in inducing short-term excessive dilatation and long-term intimal hyperplasia of vein graft. 2. Muscular covering is of priority in blood vessel graft.