Luthern is a municipality in the district of Willisau in the Canton of Lucerne in Switzerland .

Luthern is first mentioned in 1275 as Lutrun.

Luthern has an area, as of 2006, of 37.9 km2 (14.6 sq mi). Of this area, 47.8% is used for agricultural purposes, while 47.6% is forested. Of the rest of the land, 3.5% is settled (buildings or roads) and the remainder (1.1%) is non-productive (rivers, glaciers or mountains). In the 1997 land survey, 47.49% of the total land area was forested.