The epithalamus is a dorsal posterior segment of the diencephalon (a segment in the middle of the brain also containing the hypothalamus and the thalamus) which includes the habenula, the stria medullaris and the pineal body. Its function is the connection between the limbic system to other parts of the brain.

Some functions of its components include the secretion of melatonin by the pineal gland, and the regulation of hunger and thirst by the habenula.