Effect of a neuropeptide semax is studied in 73 patients with various symptoms of posthypoxic encephalopathy in remote period. Fourteen of these patients developed a persistent vegetative state. The therapy was effective in patients with mnestic disorders; the drug effect was potentiated by an adaptogen oxiterm and by supraorbital electrophoresis. In some cases EEG showed episodes of paroxysmal activity after semax injection, and therefore, the first injection should be carried out with monitoring bioelectric activity of the brain.