Gamča (Slovak pronunciation: [ˈɡamtʂa]), today officially Gymnázium, Grösslingová 18, Bratislava, is a public coeducational gymnasium located in Bratislava, Slovakia.

It was founded in 1626 by Peter Cardinal Pazmáň (Péter Pázmany) as Collegium Posoniense.

Gamča's focus on mathematics, natural sciences and computer sciences brought 56 of its students to successfully represent Slovakia (Czechoslovakia) at the International Mathematical Olympiad, 26 students at the International Physics Olympiad and 14 at the International Olympiad in Informatics in the past 35 years.

Since 1988, the school's popular "Olympic games", OH Gamča, are held annually.

Cardinal Archbishop of Esztergom Petrus Pazmanus founded Collegium Posoniense on September 11, 1626, with the approval of the 6th Jesuit Superior General Mutio Vitelleschi and Ferdinand II, Holy Roman Emperor.