Lahn (disambiguation)
Lahn may refer to:
- the Lahn, a river in western Germany
 - Lahn, Hesse, a city that existed between 1977 and 1979 as a merger of Wetzlar and Gießen, in Hesse, Germany
 - Lahn, Lower Saxony, a municipality in the district of Emsland, Lower Saxony
 - Lahn (Wald im Pinzgau), a village in the municipality Wald im Pinzgau, Austria
 - Lähn, German name of the town Wleń in Poland
 - How to Make Millions Before Grandma Dies, known in Thai as Lahn Mah