Objective: To investigate the curative effect and histocompatibility of reconstruction of traumatic urethral defect of rabbit using urethral extracellular matrix (ECM).Methods: Urethral ECM was obtained by excision of the urethra in 20 donor rabbits.In experimental group,20rabbits were resected a 1.0 cm-1.5 cm segment of the urethra and artificially made a model of traumatic urethral defect,then reconstructed by the urethral extracellular matrix of the same length.The rabbit immunity response was assessed by lymphocyte transformation test and serum TNF-αlevel.The reconstructed urethral segments were stained with hematoxylin-eosin and Van Gieson stain and observed by histological examination postoperatively.The urethrography,urethroscopy and urodynamic examinations were performed.Results: There was no significant difference in stimulative index of lymphocyte transformation between ECM group and control group.The serum TNF-α levels of ECM group slightly rose,but the increase was not significant as compared with control group.On postoperative day 10,epithefial cell had migrated from each side and small vessels were found in the extracellular matrix.In the 3rd week,several layers of urothelium covered the whole surface of the matrix tube.In the 6th week,the disorganized arrangements of smooth muscle fibers were firstly observed by Van Gieson staining.In the 24th week,the smooth muscle cells increased and the matrix tube appeared fairly similar to normal urethral wall components.The urethroscopy and urodynamic evaluation revealed that the surface of reconstructed urethra was smooth and emiction was unobstructed.Conclusion: The urethral extracellular matrix might be an ideal and safe biomateriai for the reconstruction of urethral traumatic defect.