Lake Pergusa (Pergoussa, Πυργούσσα in Ancient Greek) is a lake in Sicily, set between a group of mountains in the Erean Mountains chain near Pergusa, 5 km from Enna, Italy.

In addition to birds, which are by far the main inhabitants of the Pergusa nature reserve, there are also interesting species of mammals, reptiles, amphibians and invertebrates found here.

In the area of Lake Pergusa, an archeological site known as Cozzo Matrice can be found.

This site essentially houses the ruins of an old fortified village, containing imposing walls constructed around the 9th millennium BC, a sacred citadel, an opulent necropolis and the remains of an ancient temple dedicated to Demeter, dating back more than 2,000 years.

An important forest and vegetation zone named Selva Pergusina (meaning "Pergusa Wood") surrounds part of the Lake Pergusa Valley, producing a striking panorama.