The Bou Regreg (Arabic: أبو رقراق) is a river in western Morocco. It flows into the Atlantic Ocean between the cities of Rabat and Salé. The mouth of this river is called Wadi Sala.

The river is 240 kilometres long, with a tidal estuary going approximately 24 kilometres upriver. Its average discharge is 23 m3/s and can reach 1500 m3/s during floods. The source of the river is 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).