〔Abstract〕 Objective To investigate the expression of sorting nexin 4(SNX4) in mouse testis and its possible role in early endosomal substance transport.Methods Real-time quantitative polymerase chain reaction(Real-timePCR) was used to detect the difference in the expression of SNX 23 family members in mouse testis. Real-time PCR was used to detect the differences in the expression of mRNA in liver, spleen, kidney, brain and testisof mice. Immunohistochemistry and immunofluorescence staining localized the localization of SNX4 and Rab5 in testis and TM4 cells. Results The relative expression of SNX 4 in the testis of mice was about( 15. 49 ± 4. 92) times that in the liver( P<0. 01). In the testis,the relative expressions of SNX1 and SNX4 in SNX family were higher.Immunohistochemical staining showed that SNX4 was localized in Sertoli cells of testis. Immunofluorescence staining showed that SNX4 and Rab family member of rat sarcoma( Ras) protein superfamily( Rab5),a marker of early endosome,were co-localized in Sertoli cell lines in testis of normal mice( TM4 cells). Conclusion SNX4 is highly expressed in Sertoli cells of mouse testis and co-localized with Rab5. The distribution of SNX4 protein suggests that it may be involved in the endosomaltransportation and sorting of Sertoli cells.