Lungs and spleens of white mice were examined after intranasal and intraperitoneal challenge with Coxiellae burnetii, respectively. As a rule, these organisms inhabit lung alveolar macrophages and spleen reticular cells’ vacuoles and are surrounded with a three-layered wall. The vacuoles seem to be formed from phagolysosomes. They are stable structures. When lodged within vacuoles for a long time, Coxiellae preserve viability. Due to the capacity of Coxiellae to parasitize in cellular phagolysosomes, one might consider Q-rickettsiosis as an ‘exoplasmic parasitosis’.