INTRODUCTION. Earlier in experimental studies, it was established that sulfate mineral drinking water (MB) under stress causes adaptation effects depending on the mode of its use — during primary prevention or treatment. The question of the role of different modes of drinking mineral water application in the formation of adaptation mechanisms remains unclear.
 AIM. To conduct a comparative analysis of the effect of sulfate MW in primary preventive and therapeutic application on the development of adaptive metabolic and ultrastructural reactions in rats in the early post-stress period.
 MATERIALS AND METHODS. The experiments were carried out on 54 white nonlinear male rats. Acute immobilization stress was modeled using the Selye method. All animals were divided into 5 groups: the 1st experimental group — the primary preventive effect of drinking sulfate MV; the 2nd experimental group — the therapeutic effect of drinking sulfate MV; the 3rd and 4th groups — controls; the 5th group — intact animals. Drinking sulfate MW (concentration of sulfate ions 1.93 g/l, mineralization 3.05 g/l) was administered intragastrically by 3 ml, a total of 18 procedures. Objects of research: liver and testes. Research methods: biochemical, light-optical, morphometric, electron microscopic. The statistical significance of the differences was assessed using the Student’s criterion.
 RESULTS AND DISCUSSION. It was found that the most pronounced development of adaptive-protective reactions (increased activity of the antioxidant system, increased protein synthesis, activation of intracellular regeneration processes) was observed with the action of MW in the primary prevention mode. At the same time, there was the formation of more powerful adaptation mechanisms associated with the additional accumulation of structural and metabolic resources that limit the development of maladaptation and pathological processes. With the therapeutic use of MW, due to post-stress disorders of the mechanisms of regulation, the processes of adaptation and compensation were weaker.
 CONCLUSION. The results reveal some features of the mechanism of action of drinking sulfate MW on the development of compensatory and adaptive processes and indicate the need for a differentiated approach in the use of drinking MW to increase their effectiveness in the comprehensive prevention and treatment of the body from the damaging effects of various stress factors.