The study of the chromatin's ultrastructure in the nuclei of hepatocytes under the adrenalin influence is very essential (e.g., the square of the perimembrane chromatin-PmCh). The experiments have been carried out on 10 male dogs. Experimental dogs received adrenalin intravenously--100 mkg per 1 kg of weight during 5 days. The pieces of tissue have been fixed by 2.5% glutaraldehyde solution ("Serva"--FRG) and postfixed by 2% four-oxide osmium, dehydrated in spirts and acetone, and poured into exposed mixtures. The ultrathin cuts have been got on ultramicrotome "LKB" (Sweden) Microscopic sections examined by electronic microscope "JEM-7" (Japan) increasing 10,000 times. Morphonutrical working have been carried out by Student method and expressed in conventional units. The relation of the area of perimembrane chromatin to the nucleus's area in hepatocytes of the controlled animals, is equal--to 0.21 and of the experimental ones--to 0.13 (decreased 1.6 times, 0.02 p 0.05).