Leaf anatomy of 10 species of the genus Teucrium L. in Iran were studied. Anatomical structure of leaves was compared in species. The most differences among species belong to the layers of palisadic and spongy parenchyma, thickness of leaf, cuticle of upper surface, size of epidermal cells and trichome types. These characters can be used in distinguishing species and infraspecific taxa and therefore have high taxonomical values.