The article describes physical and chemical characteristics, basic properties as well as mechanisms of action and impact of natural bentonites on the living organisms. The effectiveness of their use was experimentally demonstrated in optimization of metabolic processes, correction of micronutrient deficiency, improvement of nonspecific resistance of the animals. The level of phagocytic activity of the animals treated with bentonite increases by 22.6%, the intensity of phagocytosis significantly increases in 1,3–1,53 times, phagocytic number — by 108.7–116.9%. Lysozyme activity also increases in 1,72 times. The use of bentonite provides a correction of biochemical parameters of blood serum influencing the increase in the concentration of total protein by 12,4–18,6% glucose — in 1, 47–1,78 times, total calcium — by 7,5–28,9%, inorganic phosphorus — by 22,9–36,1% respectively. The high level of biological activity, therapeutic and preventive efficiency was revealed for hypotrophy, anemia, mycotoxicosis, metabolic diseases and stress of the animals. Their high prophylactic and therapeutic effect in the treatment of gastrointestinal diseases of an infectious etiology was confirmed in young pigs.