The present article is an attempt to interpret Tyrmand's 'Diary 1954' with the use of Mikhail Bakhtin's carnivalisation theory. The relationship between Diary and the reality created by social-realist texts can be put into the scheme carnival - the official culture. The literary exponent of this relationship is the grotesque, with which Tyrmand transforms the elements of the official culture. In a totalitarian country, an open criticism of the system was impossible, thus only in his Diary could Tyrmand deride with impunity the communism and the ruling party. He did that through the carnivalisation of the world presented, which related to profaning and degrading of the social-realistic sacrum. Diary writing was also linked with a katharsis that Tyrmand experienced due to the carnivalistic laugh. The theory of carnivalisation makes it possible to delineate the so far unknown elements of Tyrmand's prose.