The expression of paired immunoglobulin-like receptor B(PirB)in normal and injured spinal cord of rats was investigated.The SD rat hemi-sectioned spinal cord injury(SCI)model was established.Before and 1,3,7,10 days after SCI,the spinal cord tissues were harvested,and Western blot and immunohistochemistry were used to examine the expression and location of PirB.The results showed that the expression level of PirB in the normal spinal cord of SD rats was low.At the first day after SCI,the expression of PirB was obviously increased,and that in the injured spinal cord from the first day to the 10th day was significantly higher than in the normal spinal cord.The positive expression of PirB in neurons from different regions of gray matter of the injured spinal cord was seen.It was concluded that the expression of PirB in the normal spinal cord of rats was low.The expression of PirB in SCI was significantly increased till at least the 10th day.