Oiartzun (Spanish: Oyarzun ) is a municipality in the province of Guipúzcoa, in the Autonomous Community of the Basque Country. The town was known in Roman times as Oiasso or Oiarso.

Alfonso VIII of Castile gave Oiartzun city rights, whereupon it still took some time until the independence of Errenteria was given.

Sons and daughters of the community