Technical methods for preparation of thin sections suitable for electron microscopy, while exacting, have been developed to a point of useful application. A series of electron micrographs from such sections of the anterior lobe of the pituitary glands of normal female rats are presented. It is evident that in many respects the nuclear and cytoplasmic detail revealed surpasses that which can be achieved by light microscopy and offers great promise for research in problems of cytophysiology and pathology. The various cell forms as seen in the normal anterior pituitary are illustrated, and tentative interpretations of functional states are made. Cytologic structures clearly demonstrated include `specific' granules, mitochondria, Golgi apparatus, cytoplasmic ground substance and cell membranes. Some acidophiles contain delicate intracellular canaliculi (or lamellae), and cytoplasmic vesicles and vacuoles are prominent in certain basophiles. These alterations, which are associated with enlargement of the Golgi apparatus, are believed to reflect secretory activity.