The Gulf of Patras (Greek: Πατραϊκός Κόλπος, Patraikós Kólpos) is a branch of the Ionian Sea in Western Greece.

On the east, it is closed by the Strait of Rion between capes Rio and Antirrio, near the Rio-Antirrio bridge, that is the entrance of the Gulf of Corinth.

To the north it is bounded by the shore of Aetolia-Acarnania in continental Greece, and to the south by Achaea in the Peloponnese peninsula.

The old ports of Rio and Antirrio lie at the east end of the Gulf; there is a ferry service between them which complements the traffic over the Rio-Antirio bridge.

The gulf is rich in fish and molluscs, including sea snails and clams.