The article opens with an explanation of the topic and pointing out of the relativization of the concept of canon in the Postmodern, followed by the ‘operative definition’ of canon according to K. Nemec and M. Solar. Due to the central position of Miroslav Krleža’s plays in Gašparović’s theatre criticism and historiography, as well as to Gašparović’s Krležianic critical examination of all cultural values, Krleža’s interpretation of the Croatian dramatic canon is also discussed to an extent. The concise review of Gašparović’s work as university professor, theatre journal editor, theatre critic, scholar, dramaturg and theatre manager given here focuses on his constant commitment to the ‘open dramaturgy’ which was announced already in his essay on the possibility of critical engagement in the contemporary Croatian drama published in 1986 and further developed in his later writings on the Croatian drama of the 20th century. Gašparović’s contribution to the formation of the Croatian dramatic canon is discussed in the second part of this article: the revalorisation of Krleža’s early plays and the proposed new selection of his canonical plays in the book Dramatica krležiana; the unanswered question of whether Janko Polić Kamov’s plays have a canonical status in his monograph Kamov; the synthesis of Gašparović’s almost five-decade long studies of Croatian drama in his book Dubinski rez (Deep Cut) in which the most important chapters are dedicated to the canonical Croatian playwrights of the 20th century – from Ivo Vojnović and Krleža to Nedjeljko Fabrio, Antun Šoljan, Slobodan Šnajder and the other playwrights connected with the literary journal Krugovi (Circles) and theatrical journal Prolog.