Etoloacarnania is one of the fifty prefectures of Greece. It is located on the west. The prefecture is a combination of Aetolia and Acarnania. The capital of the prefecture, for historical reasons is Mesolonghi and the biggest city and financial center is Agrinio.

Some of the other great cities of the prefecture are Nafpaktos, Etoliko, Amfilochia, Vonitsa, Astakos and Thermo. The area was connected to Peloponnesus in 2004 through the bridge of Rio - Antirio, where the ferry boat connection is still running. The surrounding prefectures are Arta of Epirus, Karditsa of Thessaly, Evritania on the northeast and Fokida on the east. The biggest ports of the area are those of Astakos, Nafpaktos, Amfilochia and Vonitsa. It is the biggest prefecture of Greece.

The prefecture is mostly mountainous. The northwest coastline is characterized by the presence of several lagoons, especially those of Mesolonghi and Aitolikos. The longest and main river is Acheloos, which ends in delta formation in the northwest, and the largest lake Trichonida is the largest lake of the entire country (97 sq. klm.). Other lakes found in the prefecture are Evinos, Inachus and Mornos (at the borderline with Fokida and during ancient years was known as Dafnos).

The mountains of Aetoloacarnania include the Panaitoliko on the northeast, Akarnanika mountains on the west, the Valtos mountains on the northwest, Arakynthos on the south, Nafpaktia mountains on the southeast also known as Kravara and finally between Nafpaktia and Panaitoliko mountains we find the Lidoriki mountains.

The climate varies from warm summers with a lot of humidity and in mild winters in the low-lying areas. Cold winters in the mountainous areas, while is higher altitudes even the summers are cool.