Abstract: Objective: To investigate the role of amniotic membrane in the prevention of epidural adhesion after laminectomy and to find out the related mechanism.Methods: Laminectomy was performed in the lumbar 5 sector of 60 rabbits,and the exposed dura mater was covered with amniotic membrane(group AM),chitosan membrane(group CHS),and no covering in the control group(group CON) respectively.Five animals in each group were sacrificed at 2,4,8,12 weeks postoperatively.By using a double blind protocol,the specimens were prepared for histological study and computer-assisted image analysis.Results: In the control group,the adhesion of the dura mater to the scar tissue occurred to the entire exposed surface and the extradural space almost disappeared.In group AM and CHS,the formation of epidural scar was much less than that in the control group.The dura mater was smooth and a gap had formed in the epidural cavity.The epidural space was well preserved.Group AM had the lowest adhesion evaluation index,and there was statistical difference(P<0.05-P<0.01).Conclusions: Putting a suitable obstructer between the dura mater and the erector spinal muscle can prevent the extension of epidural scar into the spinal canal and make dura exempted from adhesion.Amniotic membrane is an effective biocompatible material in preventing epidural scar.