Hepatic trematode (Fasciola hepatica ) has a complex life cycle. The mature form is located in the bile ducts of herbivores (cattle, sheep, goats and sometimes humans) being the final hosts. Hepatic trematode is an obligatory parasite, it cannot exist in a free-living form. Infection causes a disease called fasciolosis. In the acute phase, when the parasite penetrates the liver parenchyma, an acute hepatitis is developed. This hepatitis is manifested by significant hyperemia and enlargement of the liver. The surface of the liver is covered with small holes that are places of entry of young parasites into the liver parenchyma. With intense invasions, peritonitis is also observed. Hepatic lymph nodes are enlarged and swollen. In the case of very severe invasions internal bleeding from the liver is possible, which results in significant amounts of blood in the abdominal cavity. Over time, damage to the liver parenchyma increases. The ducts hollowed out by migrating trematodes are filled with blood and damaged liver tissue. Infiltrates of macrophages and eosinophils are observed. In the next stage the cavities become filled with granulation tissue, which scars over time.