Montreuillon is a commune in the Nièvre department in central France.
At the 1999 census, the population was 308. On 1 January 2007, the estimate was 311.
Montreuillon was formerly the official centre of the Eurozone
It is the site of an impressive aqueduct over which runs the feeder canal linking the Pannecière reservoir with the Canal du Nivernais.