The master thesis wants to show the development of Czech and Slovene avant-garde in the first half of the 20 th century, while also analyzing potential relations between the Slovene and Czech in the field of avant-garde poetry. In the first part the thesis offers an overview of avant-garde art theories and by doing so strictly excludes expressionism and modernism from the range of avant-garde. From three of the most representative theories of avant-garde the thesis synthesizes a model, which can justify Czech as well as Slovene poetry as avant-garde. In the second and third part the thesis shows a systematical overview of both avant-gardes' development, concluding that common ground for both can be found in modernist and contemporary avant-garde movements. In Czechoslovakia proletariat art forms in the first phase, influenced by futurism, later in the context of the group Devětsil developing to poetism, an original Czech avant garde movement, which shows mainly influences of Russian constructivism. In the third phase, after the group falls apart, poetism develops to surrealism. In Slovenia the first phase is connected to Podbevšek, also influenced by futurism and his collection Človek z bombami. The second phase is set in Kosovel's constructive constructivist production, which was published decades after his death. The third phase constitutes of Slovene constructivism of Černigoj and Delak. In the fourth part the thesis analyses potential reception and influences, where we find that the influence from Slovene avantgarde is rather improbable, because in its time Slovene avant-garde was locally contained and not known internationally. On the other hand, Slovene newspapers have reports of cultural events in Czechoslovakia, however there are not any notices of avantgarde art. Information about Czech avant-garde was thus transmitted only to a lesser extent, so based on the material that is available up until now we cannot talk of a direct influence of the Czech on Slovene avant-garde. We can mostly talk about a possibility or random similarities between the avant-garde poetry of both nations. The master thesis offers a review of the Czech avant-garde, which in the context of influences on the Slovene literature was not yet widely researched. Thus it also offers starting points for possible further research, especially regarding possible cultural influence between both nations.