Succinic acid and its salts (succinates) positively affect the oxygenation of the internal environment, stabilize the structure and functional activity of mitochondria, and normalize the ion metabolism in the cell. Separate clinical studies and experimental surveys confirmed that having low toxicity succinic acid has well-manifested antioxidant, immunostimulating, adaptogenic properties. In this study, we determined the influence of succinic acid on the organism of laboratory animals against the backround of high-fat diet: the changes in body weight, indices of the mass of the internal organs, blood parameters and the changes in the intestinal microbiota were determined. For the experiment, we formed three experimental and three control groups of male white mice. The animals of the control group received 0.5% solution of succinic acid instead of water. In the experiment, we determined that succinic acid has no effect on the intensity of growth of weight of young mice against the background of excessive fat in their diet. Excessive consumption of fat by male mice leads to mainly disorders in the functioning of the liver, excretory and the immune systems. High-fat diet of mice is accompanied by impaired hepatic function, manifested in sharp hypoproteinemia due to globulins, increase in the activity of hepatic enzymes against the background of reduced activity of alkaline phosphatase, increase in the level of bilirubin, and decrease in glucose. Excess of fat in the diet leads to malfunctioning of the excretory system, manifested in the reduced index of kidneys’ weight, high content of creatinine and reduced level of urea in the blood. Addition of succinic acid has a positive effect on the functional condition of the liver and the kidneys, especially noticeable during long-term intake. High-fat diet causes disorders in the functioning of the organs of blood circulation and immune protection, accompanied by decrease in the relative mass of the thymus and spleen, low content of hemoglobin and the number of erythrocytes, but has no significant effect on the content of other cellular elements in the blood. By the middle of the experiment, succinic acid had exacerbated these processes compared to the control, but by the end of the experiment, by contrast, these processes were alleviated. Addition of the succinic acid to high-fat diet contributed to the change in the quantitative composition of the main representatives of the obligatory microbiota (Bifidobacterium spp., Lactobacillus spp. and typical Escherichia coli) in the laboratory animals. Such changes in the intestinal microbiota may lead to such consequences as reproduction of the facultative microflora, and, thus, development of various diseases.