The former French Catholic diocese of Rieux existed from 1317 until the French Revolution. It was based at Rieux-Volvestre, south-west France, in the modern department of Haute-Garonne.
It was erected by Pope John XXII, as suffragan to the archiepiscopal See of Toulouse.
Coordinates: 43°15′30″N 1°12′12″E / 43.2583°N 1.2033°E