Odorant-binding protein selectively binds various odorants and is discretely concentrated in nasal mucosa and secretions. We have localized rat odorant-binding protein mRNA to the lateral nasal gland by in situ hybridization histochemistry and have also localized the protein to this gland by immunohistochemistry and by tritiated-odorant autoradiography. The lateral nasal gland extends a long duct toward the external nares. Odorant-binding protein, released from this duct, may transport odorants to olfactory receptor neurons.