Losna is a lake situated within the municipalities of Ringebu and Øyer in Innlandet county, Norway.

It forms part of the Gudbrandsdalslågen river, which, in this region, is so broad and runs so slowly that this stretch is recognized as a lake.

The maximum depth of the lake is 55 metres (180 ft) below the surface.

The European route E6 highway and the Dovrebanen railway line both run along the shores of the lake.

This article related to a lake in Innlandet in Norway is a stub.