OBJECTIVE To explore the regularity of the change of S-100 protein in degenerative nerve after different pathological brachial plexus injuries. METHODS Eighty SD rats were randomly divided into two groups, right C5, C6 preganglionic injury, and postganglionic injury. The distribution and content of S-100 protein in distal degenerative nerve were detected after 1, 2, 3 and 6 months of injury by immunohistochemical methods. RESULTS The S-100 protein was mainly distributed along the axons. The S-100 protein positive axons of each time interval decreased after operation, with significant difference from normal nerves (P lt; 0.01). There was no statistically significant difference among 1, 2, 3 and 6 months group (P gt; 0.05). The S-100 protein stain of postganglionic group was negative. CONCLUSION In preganglionic injury, the functional expression of Schwann’s cells in the distal stump keeps at a certain level and for a certain period. Since Schwann’s cell has inductive effect on nerve regeneration, it suggests that the distal nerve stump in preganglionic injury can be used as nerve grafts.