Tin Ujević is the author of a fruitful, diverse opus of poetry and prose; even during his lifetime, his works of poetry ensured him a place among Croatia's twentieth-century greats. During his lifetime, he published five volumes of poetry: Lelek sebra (1920), Kolajna (1926), Auto na korzu (1932), Ojađeno zvono (1933) and Žedan kamen na studencu (1954); the volume of his unpublished poetry nearly equals the amount published. His long poetic career, stretching nearly half a century, was marked with frequent changes; from book to book, Ujević revealed a new poetic voice, a new conception of poetry, a new perception of lyricism; the same goes for the numerous poems he published throughout the decades in periodicals only. The fields of literary criticism and literary history thus view Ujević as a poet of discontinuity, of fractures, of sudden and final breaks with his own poetic practice, and as an eternal seeker of new possibilities in poetic expression. Significantly, changes in Ujević's approach to poetry were not only the result of his immanent development as an artist; these changes were greatly impacted by his discovery of new authors and literature, whose influence caused him to change his poetic language – to a greater degree than he was willing to admit. In this sense, particular phases of Ujević's poetic opus are dialogically related to various traditions and poetic styles, making his work exceptionally suitable for intertextual analysis. Aside from this, traces of various literary traditions are abundant in Ujević's work on many textual levels, from motifs, themes, symbolism, and metaphor, to various lyrical forms and genres. In this sense, his work is exceptionally fruitful terrain for the intertextual researcher. In my doctorate dissertation, I intend to undertake such an analysis of Ujević's opus in hopes of establishing and elaborating upon the intertextual connections established in his work; I also intend to offer a typology of these connections to serve as a basis for the periodisation of Ujević's poetry. The first section will provide a brief overview of the history of intertextual theory, as well as a summary of the work of its main theoreticians, such as Mihail Bahtin, Julia Kristeva, Roland Barthes, Michael Riffaterre, Gérard Genette, and Dubravka Oraić Tolić. I will also show how the concept of "intertextuality" is interpreted and used in this research, for which reason I differentiate the semantic scope of the concept into multiple levels, such as specific intertextuality, general intertextuality, and absolute intertextuality. After the introductory section, I will analyse Ujević's entire poetic opus. I will begin with his poems published in the anthology Hrvatska mlada lirika in order to show that, even in his early phase, Ujević built his texts on a foundation consisting of numerous segments of literary tradition, from recognisable literary topos to particular genres of poetry. My analysis of the collections Lelek sebra and Kolajna will begin from current Croatian studies and comparative literary research on elements of Dante, Petrarch, and Baudelaire in these collections in order to deepen and systematise the detected intertextual connections. Finally, I shall offer my own reading of Ujević's Kolajna in the context of chansonnier poetry in order to show how Ujević typically makes use of this distinguished poetic genre, as well as how he reinterprets some of the most common features of the love lyric sequence in order to build a modern poetic cycle. I shall display the metafictional elements of Ujević's poetry in the first part of the collection Auto na korzu, which still relies on the troubadours and Petrarch as intertext, but which also now show self-reflexive references to the process of creating poetry. I shall approach the second part of this same collection and Ujević’s radical poems written during the 1920s, most of which were only ever published in periodicals, as a whole, to show reflections of avant-garde trends in Ujević's poetry. Acceptance of certain poetic principles manifested in poetics of especially Futurism and Simultaneism brought the expressive capabilities of Ujević’s poetic language to the very limits of intelligibility. In the last phase of Ujević's work, I shall analyse his collections Ojađeno zvono and Žedan kamen na studencu, as well as poems published in periodicals from 1930-1955 in order to demonstrate that they display a different interpretation of intertextuality. The dominant intertextual reference in this part of Ujević's opus is the work of Émile Verhaeren, although viewed as a whole, no intertextuality in the sense of the previous collections can be identified. Generally, Ujević's late poetry is relatively conventional in terms of form and rhetoric, however his voluminous poetic production reveals certain types of poetic text to which I shall pay special attention. This overview of Ujević's poetry from an intertextual perspective will show conclusively the course of his poetic development as related to different kinds of intertext, as well as how the referential framework within which he created one of the most outstanding bodies of modern Croatian literary work changed over time.