OBJECTIVE: To study the expression of interleukin-1 receptor in normal mice sciatic nerves and in transected sciatic nerves treated with or without extrinsic interleukin-1 locally at different periods. METHODS: Seventy-two KM mice were equally divided into two groups. All the left sciatic nerves were transected. The stumps in experimental group were soaked in liquid with interleukin-1, whereas those in control group without interleukin-1. Then all the stumps were repaired end to end. At the 3rd hour, 1st day, 3rd day, 7th day, 14th day, and 28th day after operation respectively, every proximal stump was dissected and the expression of interleukin-1 receptor was carried out by immunohistochemistry method (LSAB method). The expression level of interleukin-1 of ten normal sciatic nerves of mice was studied, too. RESULTS: Normal nerves showed interleukin-1 receptor expression on the membrane of Schwann cells. After nerve injury, the interleukin-1 receptor expression increased biphasically in both groups, but the intensity of increase was lower in the experimental group than in the control group. CONCLUSION: Schwann cell is the target cell of interleukin-1.