The Collegiate church of Saint Ursus (Italian: Collegiata di Sant'Orso, French: Collégiale de Saint-Ours) is a collegiate church in Aosta, northern Italy, dedicated to Saint Ursus of Aosta.
The original church had a single hall, delimited by a semicircular apse. It was entirely rebuilt during the 9th century, during the Carolingian age. Later, bishop Anselm of Aosta further renovated the church, introducing a basilica plan with three naves with wooden trusses. These were replaced by Gothic cross vaults in the 15th century.