Thesis introduces the main theoretic facts about play, performance and happening. This serves as a foundation for comparing two different group of artists -Theater of Pupilija Ferkeverk and Group OHO. The main question of the thesis is: Whether Slovene avant-garde performances and happenings at the end of the 1960s and 1970s are comparable to the European and global production? Performance of Pupilija, papa Pupilo pa Pupilčki brought in Slovenian theatre new guidelines and outlined new borders (or removed them) between traditional theatre and performance. The audience was confronted with real, physical and psychological acts from real life, which forced them to look at the theatre from a different angle. In performance they brought together scenes that were connected just associatively. Actors were not playing traditional parts from dramatic work, but rather some general roles, e.g. Snow White, Anka or their role was not named. They tried to bring freedom into the new theatre. Group OHO brought into the Slovenian grounds the whole new conception of performativity - happenings. Their happenings were not some magnificent spectacles, they were the acts done from the interest for things and reistic philosophy. They did not consider their happenings to be political acts, but rather gifts for people of Ljubljana e.g. for New Year (happening Triglav). Nevertheless, some interpretations pointed out their ideological potential.