During the last decade an increasing number of peptides has been demonstrated in fibres of various origins innervating the mammalian pineal gland. These neuropeptides have been postulated to control, together with norepinephrine, the activity of the pineal gland whose main function is to synthesise and release melatonin on a nycthemeral and seasonal basis. This review will summarise our present knowledge on the presence, origin and role of neuropeptides in the mammalian pineal gland.