In this tutorial, we will learn the neuroanatomy of the diencephalon. Key structures/terms: thalamus, thalamic nuclei and related fiber tracts, metathalamus, medial geniculate nucleus, lateral geniculate nucleus, subthalamus, subthalamic nucleus, zona incerta, nuclei of the fields of Forel, hypothalamus, hypothalamic nuclei and related fiber tracts, mammillary bodies, neurohypophysis, posterior lobe of the pituitary body, infundibulum, epithalamus, habenula, pineal gland, prectectal structures, pretectal area, pretectal nuclei, subcommissural organ, posterior commissure, habenular commissure, lamina terminalis, subcallosal gyrus of the limbic lobe, optic chiasm, tuber cinereum, median eminence, pituitary stalk, neural lobe, hypothalamohypophysial tract, Rathke's pouch, adenohypophysis, hypothalamohypophysial venous portal system, midbrain, superior and inferior colliculi, stria medullaris thalami, septal nuclei, anterior commissure, column of the fornix, corpus callosum, body of the fornix, body of the lateral ventricle, internal capsule, pons, cerebral peduncle, interpeduncular cistern, supramammillary commissure.