Hodh El Gharbi (Arabic: ولاية الحوض الغربي) is a region in southern Mauritania. Its capital is Ayoun el Atrous. The region borders the Mauritanian regions of Tagant to the north, Hodh Ech Chargui to the east, Mali country to the south and Assaba to the west. A piece of Malian territory protrudes into the region.