Patagosaurus (PAT-a-go-SAWR-us) (meaning "big footed lizard") was a large herbivorous dinosaur from the long-necked group Sauropoda. It reached the length of 18 metres. Similar to other primitive eusauropods, it was rather heavily build and similar to Cetiosaurus in general appearance.

It is known from a dozen individuals, though some referred material may belong to another related dinosaur genus. It lived during the Callovian of the Middle Jurassic (163-161 million years ago) in what is now called Argentina. Other Argentinian dinosaurs living approximately at the same time were Piatnitzkysaurus, Condorraptor and Amygdalodon.

It was described by Jose Bonaparte in 1979.

Patagosaurus was a herbivorous dinosaur.