Acqualagna (Italian: [akkwaˈlaɲɲa]) is a comune (municipality) in the Province of Pesaro e Urbino in the Italian region Marche, located about 70 kilometres (43 mi) west of Ancona and about 40 kilometres (25 mi) southwest of Pesaro.

As of 31 December 2004, it had a population of 4,304 and an area of 50.8 square kilometres (19.6 sq mi).

The current name derives from the Latin name Aqua Lanea, meaning "Water Slaughter", and which remembered the battle of Gualdo Tadino fought nearby between Totila's Ostrogoth and Narses's Byzantine armies during the Gothic Wars.

In the neighbourhood existed the Roman town of Pitinum Mergens, destroyed by Alarich I.

In 1901, notorious brigand Giuseppe Musolino was caught in Acqualagna after he had escaped prison more than two years prior.