Sumerian religion was the religion practiced and adhered to by the people of Sumer, the first literate civilization of ancient Mesopotamia. The Sumerians regarded their divinities as responsible for all matters pertaining to the natural and social orders.

Before the beginning of kingship in Sumer, the city-states were effectively ruled by theocratic priests and religious officials. Later, this role was supplanted by kings, but priests continued to exert great influence on Sumerian society. In early times, Sumerian temples were simple, one-room structures, sometimes built on elevated platforms. Towards the end of Sumerian civilization, these temples developed into ziggurats--tall, pyramidal structures with sanctuaries at the tops.