Ayoun al Atrous (also known as Aioun el Atrouss) (Arabic: عيون العتروس) is a town in southern Mauritania. It is located at around 16°40′0″N 9°37′0″W. It is the capital of Hodh El Gharbi region.
The city is served by the Aioun el Atrouss Airport, 6 kilometres (4 mi) north-west of the city. The town is located in the southern area of the Aoukar, a former lake basin.
Ayoun al Atrous was one of the stops in the 2007 Dakar Rally.