The aim: The objective of our study was to evaluate the features of ultramorphometric characteristics of exocrine parenchyma and microvasculature of the pancreas in the presence of moderate dehydration by means of an experiment in laboratory rats. Materials and methods: The experiment involved 20 mature white male rats divided into 2 groups: control and experimental (10 rats each). In the experimental group, moderate dehydration was simulated, i.e. the animals were deprived of water for 7 days, while the control rats were provided with a normal water supply during the study. Pancreatic parenchyma samples were fixed in phosphate-buffered glutaraldehyde solution and post-fixed in osmium tetroxide solution, dehydrated and embedded in a mixture of epoxy resins. Ultrastructural analysis was performed using JEOL JEM-1230 transmission electron microscope (Japan). Results: Pancreatic electron microscopy in the presence of moderate dehydration demonstrated statistically significant changes in exocrinocytes area and exocrinocyte nucleus area which increased by 8.02% (p = 0.028) and 40.28% (p < 0.001), respectively. Among the vessels of microcirculation, the largest changes occurred in the capillaries: their lumen narrowed by 22.34% (p = 0.002) as compared with the control group. The cytoplasm of endothelial cells contained a large number of vacuoles and micropinocytotic vesicles. Conclusions: Among the organelles of exocrinocytes, mitochondria appeared the most vulnerable to the effects of dehydration. They demonstrated polymorphic changes: a part of the mitochondria was hypotrophic and had partially reduced cristae, and another part was hypertrophic.