Irun (Basque: Irun, Spanish: Irún) is a town of the Bidasoaldea region in the province of Gipuzkoa in the Basque Autonomous Community, Spain.

It lies on the foundations of the ancient Oiasso, cited as a Roman-Vasconic town.

During the Spanish Civil War, the city was site of the 1936 Battle of Irun, which ended with a strategic victory for the Nationalist forces.

One of the biggest towns in Gipuzkoa, its location on the border between Spain and France, across the Bidasoa river from Hendaye, has made Irun into a commercial and logistic centre. Irun railway station is a major break-of-gauge where the SNCF 1,435 mm (4 ft 8+1⁄2 in) standard gauge rails meet the 1,668 mm (5 ft 5+21⁄32 in) broad gauge Renfe ones.

Currently Irun has a fairground with a modern exhibition and telecommunication facilities, just some 100 metres away from the actual border at the Santiago Bridge (river Bidasoa).

Irun is part of the conurbation of Txingudi bay with Hondarribia and Hendaye; the town is also within the area of the Eurocité Basque Bayonne-San Sebastián, a European economic interest grouping. (fr)

One of its main festivals is the Alarde de San Marcial, a parade recreating an episode of the Peninsular War, held every year on 30 June.

There are hot mineral springs in the town.