Objective:To observe the expression and distribution of β-galactosidase in the central nervous system(CNS) of adult ROSA26 mouse. Methods:X-Gal histochemistry combined with Nissl’s or immunohistochemistry double-staining was performed to localize β-gal activity in the ROSA26 mouse CNS. Results:X-Gal histochemistry staining showed that transgenic β-gal reaction products were throughout the central nervous system, but mainly located at the grey matter. X-Gal and Nissl’s double-staining showed that β-gal expressed in neurons, ependymal cells and choroid plexus cells. X-Gal histochemistry combined with immunohistochemistry further revealed that β-galactosidase was ubiquitous expression in neurons except astrocytes. Conclusion:β-gal is extensively and stably expressed in the ROSA26 mouse CNS. This transgenic line may be useful in nerve cell culture, transplantation and other neurobiological studies.