The paper summarizes the most important knowledge of Q fever and its causative agent Coxiella burnetti since the first descriptions of nosologic unit and causative agent until now. With respect to disease occurrence, distribution and importance the attention is focused on the territory of the former Czechoslovakia, i.e. currently on the territories of the Czech Republic and Slovak Republic. Taking into account normal occurrence of C. burnetii in cows which is however shown in latent form only, taking into account that no cases of human clinical infections related to these latent infections in cattle have been reported at present either in the territory of the Czch Republic or of the Slovak Republic, and considering that the results of experimental infections in sheep by the autochthonous strain of C. burnetii did not reveal its virulence, it can be stated that the strains of C. burnetti currently circulating on cattle farms are little virulent or even avirulent. This decrease in virulence can be ascribed to repeated subcultures of C. burnetti strains in cattle populations excluding ticks from this circulation. Q fever prevention should currently include measures to avoid in the territories of the Czech and Slovak Republics uncontrolled imports of infected animals and/or contaminated raw materials from animal or plant sources to introduce foreign fully virulent strains that can cause clinical infections both in humans and in domestic animals.