plagues of Egypt, in the Bible, the plagues and other troubles brought on Egypt by God through the hands of Moses, because Pharaoh would not let the people of Israel go out of Egypt. The account, in the Book of Exodus, tells how Pharaoh relented each time until the plague was removed, then hardened his heart; in the end he let the children of Israel go, only to pursue them into the Red Sea. The plagues were 10 in number: plague of blood by which the waters of Egypt were turned to blood; plague of frogs; plague of lice; plague of flies; plague of murrain, by which all the cattle of Egypt and none of the Israelites' cattle were killed; plague of boils; plague of hail; plague of locusts; plague of darkness, by which darkness covered Egypt for three days; plague of the first-born, by which all the first-born of Egypt were killed. By tradition the first Passover was observed the night of the 10th plague. After it the Israelites left Egypt.