This article is about the medieval French currency, not the European Currency Unit (ECU).

The term écu may refer to one of several French coins. The first écu was a gold coin minted during the reign of Louis IX of France, in 1266. The value of the écu varied considerably over time, and silver coins known as écu d'argent were also introduced. From 1484 on, the écu was the only French gold coin. It disappeared during the French Revolution.

Ecu (from Latin scutum) means shield, and the coin was so called because its design included a shield bearing a coat of arms. The word is related to scudo and escudo.