Non-absorbable microsuture has been the usual repair method for peripheral nerve injury. Sutureless method using fibrin adhesive may offer an alternative to traditional suture tchniques. We compared two repair methods, experimentally; primary suture and fibrin adhesives repair in allograft and autograft. Twenty white rats were reexplored at 3 weeks and examined, histologically. The results were as follows: 1. In all experimental groups, failure of repair was not observed grossly. 2. Light microscopically, more inflammatory cell infiltration was noted in fibrin adhesives group. In allograft group, graft segment was replaced by adipose tissue and fibrous tissue with scattered foci of lymphocytic infiltration, and proximal end of graft was partially approximated with proximal end of cutted nerve by fibrous tissue, but distal end was not approximated. In autograft group, graft segment was partially replaced by fibrous tissue and approximated incompletely. In primary suture group, suture site was tightly approximated, and expanded by proliferated and intermingled fibroblasts and Schwann cells. 3. On immunohistochemical examination for S-100 protein, in primary suture and autograft group, grodual decrease of reactive cells were observed from proximal to distal part, showing Wallerian degeneration and nerve regeneration were also observed. In allograft group, few reactive cells were scattered with abundant nonreactive fibroblasts. 4. On ultrastructural examination of similar level of distal part of cut nerve, in autograft group, abundant collagen fibers and small numbers of axons, and Schwann cells embracing few nonmyelinated regenerating axons were revealed. In allograft group, collagen fibers were compact and proliferated Schwann cells was more abundant rather than axons. In primary suture group, collagen fibers were loosely arranged, and proliferated Schwann cells and axons were more abundant than in fibrin adhesives group and Schwann cells embraced more nonmyelinated regenerating axons. From the above results, the degree of approximation in repair site and regenerating activity in injured nerve is more effective and active in primary suture group than in fibrin adhesives repair group. Therefore, the author recommends fibrir, adhesives be used as an additional procedure to suture method.