The Gulf of Piran or Piran Bay (Slovene: Piranski zaliv, Croatian: Piranski zaljev or Savudrijska vala, Italian: Baia di Pirano) is located in the northern part of the Adriatic Sea, and is a part of the southernmost tip of the Gulf of Trieste.

On the eastern Slovenian coast lies the town of Piran, and the settlements Portorož and Lucija.

On the southern Croatian coast are tourist camps of Crveni Vrh and Kanegra, built in the 1980s.

Along the mouth of the Dragonja lie the Sečovlje saltpans, covering an area of 650 hectares (1,600 acres).

The Gulf area has been a theatre of a maritime and land border dispute between Slovenia and Croatia.