The analysis of bacteriological changes in hare internal organs has been performed in the paper. The assessment was made with regards to the individual condition of animals. Anatomical and pathological changes were found in 80% of the hare from the obtained sample. These occurred regardless of the age and gender of animals and were mostly inflammatory infiltrates and necrosis in the testes of males as well as inflammatory infiltrates of the liver and emphysema found in both males and females. There was also an increase in flora of two bacterial strains in hares internal organs. The Nocardia strain was found in the testes of two individuals, whereas the Providencia rustigianii strain was found, at various severity levels, in the liver, kidneys, lungs and heart of males and females, regardless of their age. Isolated strain of Providencia rustigianii proved to be resistant to three antibiotics, while Nocardia strain to one of the antibiotics used. The analyses carried out indicate that in addition to population and ecological factors resulting from environmental changes, a number of pathogenic agents, including the presence of bacteria that have not been described in this animal species, are a significant factor limiting the reproductive potential of the population. Therefore, disturbances of physiological processes having a diverse etiological background can lead to numerous anatomical and pathological changes, and thus increase susceptibility to diseases and falls of animals, and at the same time, deepen the ongoing regress of this species population. Not without significance is the fact that the described changes were found regardless of the gender and age of animals.