Oleggio is a comune (municipality) in the Province of Novara in the Italian region Piedmont, located about 90 km northeast of Turin and about 15 km north of Novara. As of 31 December 2004, it had a population of 12,490 and an area of 37.8 km². Oleggio borders the following municipalities: Bellinzago Novarese, Marano Ticino, Mezzomerico, Momo, Vaprio d'Agogna, and Vizzola Ticino.