Fyrisån is a river in the Swedish province of Uppland, which passes the city of Uppsala and ends in lake Mälaren.

It was formerly called the Full or the Sala river — Sala referred to the halls (Up-Salir) of the Swedish kings at Old Uppsala — but its name was changed in the 17th century in remembrance of the Fyrisvellir, which was long gone, due to agriculture, but famous from Norse mythology.