Aim: The aim of the study was to determine the characteristics of structural changes in the jejunum and ileum of experimental animals of different ages following cadmium chloride intoxication. Materials and Methods: Experimental studies were conducted on 60 white laboratory male rats, both prepubertal and pubertal, with body weights of 80–100 g and 190–220 g, respectively. All animals were divided into three groups. Of these, 12 animals constituted the intact control group, which was divided into two subgroups: 6 sexually immature white rats and 6 sexually mature animals. The experimental animals comprised two groups, each with two subgroups. The second group included 24 immature rats, of which 12 were removed from the experiment on the 7th day and 12 on the 14th day after cadmium chloride poisoning. Group 3 consisted of 24 experimental animals, of which 10 were removed from the experiment on day 7 and 14 two weeks after cadmium intoxication. Poisoning of the experimental white rats with a cadmium chloride solution was performed intraperitoneally at a dose of 6 mg/kg body weight. It was used electron microscopic examination. Results: Cadmium chloride exposure causes structural changes in the jejunum and ileum. The observed phenomena are more pronounced in the jejunum, which is explained by its greater functional activity compared to the ileal segment of the small intestine. Exotoxin disrupts the function of proteins and cell membranes, affects metabolic processes in the small intestine and its epithelium. Under electron microscopy, the surface of the ciliated epithelial cells appeared as a series of microvilli closely arranged next to one another. A functional feature of the apical membrane of epithelial cells is a pronounced endocytosis, manifested by the detachment of endocytic vesicles containing substrates from the base of the microvilli. Changes in the ultrastructure of the microvilli of the brush border at the apical pole of columnar epithelial cells may indicate disturbances in parietal digestion and absorption processes. On the 7th day after cadmium chloride poisoning, exposure to exogenous factors results in thickening of the subepithelial mucus layer, which may be interpreted as the organ’s protective response to a chemical irritant. Cadmium chloride intoxication in experimental animals leads to the suppression of regenerative processes against the background of morphological changes in the structure of ciliated epithelial cells, which is associated with cadmium accumulation in the cells. Conclussion: The destructive changes in the organization of organelles, the cytoplasmic membrane of epithelial cells, and the basement membrane indicate disturbances in intracellular bioenergetics, the protein-synthesizing apparatus, and the transcellular transport of substances through the capillary network, leading to changes in the properties of the capillaries themselves.