Toxic liver injury poses an important heath problem in occupational medicine. Toxic response of this organ may arise from acute or chronic exposure to different substances. The final toxicological response to different toxicants may be defined as the egeneration of cells, loss of their function or necrosis. The morphology of toxic drug- or chemical-induced liver injury usually differentiates into one of the following phenotypes: cholestatic injury, hepato- cellular injury, often associated with elevated liver enzymes, mitochondrial injuries and delayed immunological injury. In this article, the authors present current knowledge of the pathogenesis of morphological changes in hepatocytes as the result of exposure to xenobiotics.