Melchnau is a municipality in the district of Aarwangen in the canton of Bern in Switzerland. Melchnau celebrated its 900th anniversary in 2000. The earliest written evidence for the town was written in c. 1100. In the last century Melchnau has developed from a farming town to a municipality with a diversified economy. As well as small businesses such as light industry (for example Lanten Textiles) have emerged. In 1917 a narrow-gauge railway was opened between Langenthal and Melchnau, which in 1982 was superseded by buses. The railway and the station remain, and are now used occasionally for special events.