The Leitzaran (pronounced [leiˈts̻aɾan], or Leizarán in Spanish) is a river and a valley in the Navarre and the Basque Country (Spain).

[1] The Gipuzkoan part of its basin is known as "Valle de Leizaran" (Leitzaran Valley, while "Leitzaran" means 'the Leitza valley' in Basque), and it mostly shapes up in the "Macizo de Cinco Villas", formed by materials formed in the Paleozoic (concretely in the Carboniferous), mostly slate and sandstone, fold during the Hercynian orogeny.

The gipuscoan Leitzaran is bounded in the east by the river Urumea’s valley, divided by the Adarra-Mandoegi mountain chain.

The shorelines of the Leitzaran and those of its tributaries Ubaran (Ubane) and Malo were declared Protected Biotopes on 29 September 1995.

Afterwards, its two ends were lengthened to Pamplona and to Lasarte, a place where it joined up to the Ferrocarriles Vascongados (Basque Railways), where it could provide services to Donostia (San Sebastián).