It was established that semax and mexidol significantly reduced neurological deficiency and increased the survival in rats with model brain ischemia induced by the bilateral ligation of common carotid arteries. Mexidol exhibited a linear dose-effect relationship (in a range of doses from 30 to 120 mg/kg per day), while the effect of semax decreased with increasing dose (in a dose range from 0.3 to 1.2 mg/kg per day). Preventive course administration of semax and mexidol considerably reduced neurologic deficiency and amnesia in a step-down passive avoidance situation in rats with model brain ischemia caused by gravitation overload.