A scientific paper is devoted to studying histomorphology of healthy cats’ pancreas under acute pancreatitis. A pancreas was taken for a histological analysis (n = 6 in each group) from healthy cats, who died because of fatal injuries. The material under acute pancreatitis was taken in a scientific work-training clinic from the cats who died because of the pathalogical processes of a given pathology, or sick animals were put to death because of their critical condition and upon the consent of animal’s owner. Histological analysis of pancreas tissue were carried out in the laboratory of pathomorphology which is under the jurisdiction of the Department of Anatomy and Histology of Polissia National University. Histologic sections (from 8 to 12 micron thick) of a pancreas of both groups were painted with Ehrlich’s, Carazzi’s hematoxylin and with eozyn applying a method of Van-Gizon, after which light microscopy and microphotography of tissue specimens were carried out. Animal pancreas is of parenchymal structure, it is divided into particles consisting of pancreatic acinuses which have sharp contours of inter-acinus, internal and inter-particle canals as well as of the main canals. There are Langerhans islets (endocrine cells accumulation) among acinuses. When studying a histological structure of a gland under acute pancreatitis, some widening of inter-acinus space of a gland, a well-defined interstitial swelling and hyperemia of stroma were observed. Acinal cells (pancreatocytes of exocrine pancreas) were in a state of granular degeneration, another part of such cells was in a state of hydropic degeneration. The acinus size increased. Some acinuses lost their typical form and did not have a well-defined structure. In a gland histostructure the amount of fibroblasts, fibrocytes and synthesized collagen fibers, which were painted bright-red applying Van-Gizon method, increased. A histological structure of endocrine pancreas, which is repesented by islets of Langerhans, had some hemorrhages and burned-out cells. The islets contours were not well-defined, their capsules were ruptured on all areas. There was total necrosis of endocrine cells, islets capillaries were widened anf filled with blood. Some local hemorrhages and chromatin margination in some nuclei of different types of cells were revealed. According to organometry indices of a gland, the absolute weight of a gland (Р ≤ 0,05) increased by 1.24 time as compared with a clinically healthy animals, that accounted for становило 6.82 ± 2.31 g, and in clinically healthy cats – 5.5 ± 1.82 g. Relative gland mass increased by 1.3 times and equalled 0.50 ± 0.03 %.