The etiological agents of babesiosis are intraerythrocytic parasites of the genus Babesia, which are transmitted by ticks. The course of disease is characterized by variable severity. The risk of a complicated course of babesiosis occurs in premature infants, the elderly, splenectomized patients and other immunocompromised patients. Severe cases of this disease can lead to multiple organ dysfunction. The study focuses on the impact assessment of chronic Babesia microti invasion on the morphology and ultrastructure of rat liver. The analyzed material was comprised of liver samples collected from Wistar rats infected with a reference strain of B. microti (ATCC 30221). None of the livers collected from rats with babesiosis was enlarged. The histopathological analyses showed signs of intensive inflammatory processes, especially in the perivascular areas. The hepatic mononuclear phagocyte system was characterized by increased activity. The ultrastructral analyses confirmed disintegration of hepatocytes with vacuolization in the perivascular areas. In addition, the perisinusoidal space (space of Disse) had irregular structure. In some areas, the space of Disse was enlarged or compressed. The morphological and ultrastructural analyses of rat liver with chronic babesiosis caused by B. microti showed significant pathological changes in perivascular areas which may be the cause of hepatic dysfunction.