The Bou Regreg (Arabic: أبو رقراق) is a river located in western Morocco which discharges into the Atlantic Ocean between the cities of Rabat and Salé.

The source of the river originates from the Middle Atlas mountains at an altitude of 1627 meters on the level of Jbel Mtourzgane (province of Khemisset) and of Grou (province of Khénifra) and descends to its mouth at the Atlantic Ocean separating the cities of Rabat to the south and Salé to the north.

Water quality issues of the Bou Regreg include tidal saltwater intrusion, excessive runoff of nitrates from agricultural land uses and mercury contamination thought to arise from use of certain pesticides within the drainage basin.

[2] The Phoenicians and the Carthaginians, who founded several colonies in Morocco, inhabited the banks of the Bou Regreg approximately two kilometers from its mouth at the ancient site of Chellah.

Chellah was a significant ancient port city with remains including the Decumanus Maximus, or principal roadway, as well as those of a forum, a monumental fountain, a triumphal arch, and other Roman ruins.