In mapping the process leading from modernism to the avant-garde there were discovered many problemes topical nowadays, too. The whole system of signs in Russian and Czech literatures show the growing conflicts in the social situation, ethics and style. Comparing V. Bryusov's catastrophic and political anti-utopias with Zamyatin and Orwell the way going to the terrorism of the 21st century is remarkable. Changes in the poetics of modernistic and avant-garde prose were discovered in analyzing works by Alexei Remizov (the problem of symbol and myth), Daniil Kharms, Karel
Čapek, Viktor Pelevin and Jiří Kratochvil (the philosophy of pragmatism - a way to postmodernism). Expressive changes are taking place in two forms of the avant-garde grotesque represented either by V. Khlebnikov's poem Zangezi compared with F. Nietzsche's Also sprach Zarathustra and V. Solovyov's comedies, or the drama by D. Kharms, Elizaveta-Bam, which follow A.V. Sukhovo-Kobylin's absurd trilogy and A. Jarry's King Ubu. - The analysis of 19th and 20th century authors shows that not only the symbol but also the myth is still alive, though its manifestation is often very abstract, corresponding to the contemporary system of thought. The provocative form of art program manifested by modernism and especially the avant-garde and their inner union is one of the fundamental laws of evolution in the same way as the semantic and structure connections between literature, art, music and other forms of culture. The inner connection of modernism and the avant-garde reflected in postmodernism which develops the opinion of both the phenomena modifies them into new formations.