On the basis of histochemical characteristics it was possible to demostrate a sexual dimorphism of the tree shrew sublingual gland. Although numerous staining methods for the demonstration of mucosubstances were used in this study, only methods for the demonstration of sulfated glycoproteins (sulfomucins) were effective in demonstrating the sexual dimorphism. Numerous sulfomucin-laden cells occurred in the mucous tubules and acini of female sublingual glands, but only rarely were such cells observed in sublingual glands of male animals. Neither duct cells nor demilune cells of secretory endpieces were involved in the sexual dimorphism. No morphological sexual dimorphism was noted in tree shrew sublingual glands.