Oneiromancy is a form of divination based upon dreams; it is a system of dream interpretation that uses dreams to predict the future.

Dreams occur throughout the Tanach as omens or messages from God. Jacob dreams of a ladder to heaven; his son Joseph dreamed of his future success, additionally intrepreting the dreams of the Pharaoh of Egypt. King Solomon conversed with God in his dreams. Daniel (from the Book of Daniel) also interpreted dreams.

Aristotle and Plato both discuss dreams in various works. Artemidorus gives a list of authors mentioned in his Oneirocritica, the longest of the ancient dreambooks. All of the referenced works are lost, but fragments are preserved in Artemidorus and other ancient authors. Achmet wrote an edition of Artemidorus Oneirocritica in addition to his own. Astrampsychus was the pseudonymous author of a number of divinatory, magical and medical works, including an Oneirocriticon.