The Flumendosa is a river of southern Sardinia, Italy. With a length of , it is the second longest river of the island behind the Tirso.

The Flumendosa's springs are located in the Gennargentu massif, at the foot of the Monte Armidda; it flows into the Tyrrhenian Sea near the towns of Muravera and Villaputzu. It drains a basin of about . Before the construction of two large dams, it had a discharge of .

Rivers of Italy
Rivers of Sardinia
Rivers of the Province of South Sardinia
Drainage basins of the Tyrrhenian Sea