Ultrastructural changes were studied in the rat liver under the effect of dicyclohexylamine nitrite and oil-soluble salt of cyclohexylamine in doses of 1/10 LD50. Both substances are stated to cause damages in the structure of hepatocytes even after three days of exposure. Dicyclohexylamine nitrite shows a more pronounced effect displayed in developed dystrophic changes of cytoplasmic organelles and in the presence of osmiophil bodies.