Lajen (German: [ˈlaːjən]; Italian: Laion [laˈjon]; Ladin: Laion or Laiun) is a comune (municipality) in South Tyrol in northern Italy, located about 20 kilometres (12 mi) northeast of the city of Bolzano.

As of 30 November 2010, it had a population of 2,610 and an area of 37 square kilometres (14 sq mi).

[3] Lajen borders the following municipalities: Barbian, Kastelruth, Klausen, Urtijëi, Villanders, Villnöß and Waidbruck.

The municipality of Lajen contains the frazioni (subdivisions, mainly villages and hamlets) Albions, Freins (Fraina), Ried (Novale), St. Peter (San Pietro), Tanirz (Tanurza) and Tschöfas (Ceves).

According to the 2024 census, 86.26% of the population speak German, 7.14% Italian and 6.59% Ladin as first language.