The article presents an analysis of humorous genres of contemporary Polish, Russian and Czech folklore (jokes, sadistic poems, chastushka), inspired by real or anticipated tragic events related to the use of nuclear energy. The purpose of comparing the texts in three languages was to identify common or different motivations which contributed to writing the texts of atomic humour in the countries with various degrees of advancement of nuclear weapons. The analysis is based on the texts of jokes (approx. 200) found in the Internet (the Polish, Russian and Czech servers), materials spread through spoken communication, and non-serial publications. The analysis proved that the fear motivating the atomic jokes is not caused by the fear of the atomic technology itself, but by the fear of irresponsible people and irreversibility of their unreasonable actions.