Semax is one of the rare analogues of regulatory peptides which underwent all stages from fundamental investigations to practical usage. It has been demonstrated that this peptide is capable to stimulate operative memory and attention, to increase resistance to hypoxia and to improve brain circulation in experimental animals and human beings over prolonged period (20-24 h after intranasal administration in doses 0.015-0.050 mg/kg). Semax significantly improves memory and attention in healthy men under extreme conditions of activities. Moreover at present semax is successfully used in treatment of patients with different diseases of CNS. In the majority of cases the peptide exhibited positive effects and in no case it produced negative side actions or complications connected with its administration. There is good reason to believe that medical potentialities of semax have not been exhausted and in future new possibilities of its usage will be revealed.