The article provides data on the effectiveness of St. John's wort punctured under stress in pigs during the first to third months of their cultivation. In a pilot farm in which studies were carried out, inadequate sanitary and hygienic and zootechnical conditions for feeding and keeping pigs were identified. Under such conditions, animals are exposed to a range of stressors. Stress leads to the depletion of animals and the development of a general adaptation syndrome, which is manifested by changes in behavior, their hormonal status and, especially, the development of immunodeficiency conditions. This causes the development of alimentary anemia, delayed growth and development, reduced appetite, the development of dyspepsia, gastroenteritis and bronchopneumonia, which brings significant losses to the pig industry. To investigate the effect of the Deprim phytopreparation, which contains an extract of St. John's wort grass, clinically healthy piglets-weeds of large white breed at the age of 60 days were selected according to the principle of para-analogues, which were ill with dyspepsia in newborn age. The animals were divided into three experimental and control groups of 7 heads (n = 7) so that the average weight was not statistically different between the groups. Objectification of phytopreparation influence was performed based on results of determination of body weight gain and average daily gain, hematological and biochemical values of animals blood. It has been shown that the use of phytopreparation by piglets in two courses at a dose of 5, 10 and 15 mg/kg w. m. contributed to a positive effect on the nonspecific resistance of the body, productivity and their preservation. This is evidenced by the determination of body weight increases and average daily increases, as well as hematological indicators of animal blood.