Mexidol (100 and 200 mg/kg) and diazepam (1 and 2 mg/kg) exhibit a dose-dependent antistressor effect in the pain expectation stress test in rats (conditional emotional reflex). The effect is manifested by the normalization of both motor and somatovegetative characteristics. Paracetamol in a dose of 50 and 100 mg/kg does not possess antistressor properties. Both mexidol and paracetamol increase the threshold of pain sensitivity in the test with electric stimulation of tail in rats. Diazepam does not reduce the pain threshold in this test. The combined administration of mexidol or diazepam with paracetamol does not change the antistressor effect as compared to that of each drug alone. Mexidol, but not diazepam, enhances the effect of paracetamol on the pain threshold.