The Pineiós is a river in Peloponnese, Greece. It is probably not named after the god Peneus. Its source is on the southwestern slope of the mountain Erymanthus, near the village Kryovrysi. It empties into a bay of the Ionian Sea, southwest of Gastouni. For a part of its upper course, it forms the border between Elis and Achaea. The river flows through the plain of Elis.