The aim of the study was to investigate the effect of chondroitinase ABC (ChABC) on ephrin A4 (EphA4) expression after spinal cord impairment (SCI) in rats. Adult female SD rats were randomly divided into three groups: ChABC group, normal saline (NS) group and sham group. In the ChABC and NS group, the SCI model was produced by the spinal cord hemisection. The rats in sham group received sham operation without the spinal hemisection. ChABC and NS groups were intrathecally injected with ChABC and normal saline, respectively. At different time points after SCI, injured region of spinal cord was taken out as sample. The levels of EphA4 expression were measured by immunofluorescence technique and Western blot. And the expressions of growth associated protein 43 (GAP-43) and glial fibrillary acidic protein (GFAP) were detected using double immunofluorescent staining. Immunofluorescent results showed that, compared with that in sham group, the EphA4 expression was significantly down-regulated on 1, 3 and 7 d after SCI, then up-regulated on 14 and 21 d after SCI in NS group. In ChABC group, the level of EphA4 expression was significantly less than that in the NS group during the whole time after SCI. Western blot showed an identical result to that of immunofluorescent staining. The double labeling results showed that on 3 d after SCI, the number of GFAP, glial cells marker, positive cells in NS group was lower than that in sham group, but higher than that in ChABC group. Moreover, GAP-43 was not detected in all three groups. These results suggest that ChABC can decrease the expression level of EphA4 and reduce the number of astrocytes after SCI, thus improving microenvironment of the injured region and promoting axonal growth and extension.