This study demonstrated the immunohistochemical localization of cytoskeletal proteins, cytokeratin, desmin, vimentin, α-tubulin and α-smooth muscle actin (α-SMA) in the testes of adult and immature lesser mouse deer (Tragulus javanicus). Desmin was found in the sub-epithelial myoid cells of epididymal ducts. The immunoreactivity for vimentin was shown in the peritubular myoid cells and around the nuclei of the Sertoli cells of which the positions indicated various arrangements. In the Sertoli cells, vimentin filaments between the basement membrane and the nucleus were elongated with the migration of the nucleus toward the upper part. Furthermore, vimentin was detected in the Leydig cells and the sub-epithelial myoid cells of epididymal ducts. Alpha-tubulin was apparently extended to the tip of each Sertoli cell cytoplasm, and α-SMA was found in the peritubular myoid cells and the sub-epithelial myoid cells of epididymal ducts. On the other hand, cytokeratin and desmin were not detected in the Sertoli cells, Leydig cells, spermatogenic cells and peritubular myoid cells. In the mouse deer testes, vimentin filaments of the Sertoli cells may not be involved in the migration of the elongated spermatids and spermiation like as rat Sertoli cells because the supranuclear extension of vimentin was scanty.