Background. Intensive physical exertion is one of the stress-factors leading to the decrease of non-specific resistance of the body,  significant increase in oxygen consumption followed by activation of  the lipid peroxidation and decrease of endogenic antioxidant system efficacy. The aim of the present study was to evaluate the influence of the complex plant remedy on exercise tolerance of laboratory animals and to reveal mechanisms increasing physical endurance. Materials and methods. The experiments were carried out on white Wistar rats weighing 190-220 g. The physical endurance of the animals was estimated by recording time of weighted swimming to  complete exhaustion in the pool. The weighting was 7 % of the body  mass. The water solution of the dry extract derived from five  medicinal plants was introduced intragastrically to the animals of the experimental group at the dose of 100 mg/kg in the volume of 10  ml/kg for 7 days (once a day), an hour before testing. The content of ATP, lactic acid and pyruvic acid were determined in the skeletal  muscle homogenate; glycogen was determined in the liver  homogenate; in the blood serum there was estimated concentration  of malonic dialdehyde, the activity of catalase; the concentration of  reduced glutathione was determined in the whole blood and the  activity of superoxide dismutase was estimated in erythrocytes. Conclusion. The course introduction of the complex plant remedy to rats results in resilience to intensive physical exertion due to  optimization of energy metabolism, inhibition of free-radical  biomacromolecule oxidation processes and increase in endogenic antioxidant system activity.