The authors tested under laboratory conditions the susceptibility of five species of small laboratory animals (guinea pigs, rats, syrian and chinese hamsters and mice) to legionella infection after intraperitoneal inoculation with 10(8) cells of nine strains of legionellae of the Legionella pneumophila species. The suitability of the animal model was evaluated on the basis of clinical manifestations of the infection, pathological macroscopic changes and detection of legionellae from animal organs on CYE (Charcoal-Yeast Extract) media. The results of the analysis of experimental animal infection revealed that guinea pigs are the most suitable experimental animals for investigations and the diagnosis of legionellosis.