Introduction: Essential phospholipids (EPL) play a universal role in the human body as a source of components of cell membranes and intracellular organelles. Numerous studies have found that except of hepatoprotective properties, EPL are able to reduce the degree of oxidation stress. The important role of free radical processes in the pathogenesis of hyperthyroidism and the relation in the functioning of liver and thyroid gland are known. Purpose: to study the effects of essential phospholipids on the liver structure in hyperthyroid rats. Methods and materials: The study was conducted on noninbred albino rats weighing 180 - 220 g, and divided into 3 groups: 1st control group (6 animals) - intact rats, 2nd group (6 animals) - rats with experimental thyrotoxicosis, induced by intragastric injection of L-thyroxine (200 mcg/kg a day for 28 days); the 3rd group (9 animals) – hyperthyroid rats, additionally injected with essential phospholipids (80 mg/kg a day from 14 to 28 days). Hyperthyroidism was induced on the 14th day of experiment. Results: Morphological structure of the liver in experimental thyrotoxicosis on the 14th day was characterized by impairments violation of trabecular structure of liver lobules. Hepatocytes with hypertrophic nuclei were detected; some cells had features of lamellar degeneration. Unicellular and focal necrosis of hepatocytes, acidophilic cells like Councilman bodies were found. Hepatocytes bore signs of anisonucleosis and anisocytosis. The changes increased with hyperthyroidism duration: on the 28th day there was a significant damage to the structure of liver lobules, changes spread diffusely, necrotic hepatocytes, signs of balloon-degeneration of cytoplasm, karyopyknosis and karyolysis developed. In case of using EFL on the 28th day of experiment moderate changes in structural components of the hepatic lobules were detected. The cells were normochromic, had round nuclei with a distinct nucleolus. No pronounced signs of eosinophilic degeneration, as in the comparison group were found. Signs of balloon-degeneration were revealed only in some cells. Cells with pyknotic heterochromatic nuclei were less common. Only isolated cells became necrotic with signs of karyolysis or without nuclei, they didn’t form large areas of сoagulative necrosis. Conclusion: The results of the study showed, that essential phospholipids in rats with experimental hyperthyreosis had protective properties for hepatocytes, demonstrated by a significant reduction in their damage.