Efficiency of Semax (synthetic derivative of ACTH-4-10) was studied in 30 patients in acute period of hemispherical ischemic stroke. Control group consisted of 80 patients with the strokes analogous in severity and location of the damages and which were treated by conventional therapy. Different clinical rating scales were used for both objectivization of the severity of the patients' state and estimation of the degree of neurological defect. The control of Semax influence on the functional state of the brain included monitoring of EEG with mapping, repeated analysis of somatosensory evoked potentials and their mapping. It was established that including of Semax in combined intensive therapy of acute ischemic stroke had some influence on the rate of restoration of the damaged neurological functions in terms of increasing the regress of general cerebral and focal, especially motor disorders. The most effective daily doses were 12 mg for patients with strokes of moderate severity and 18 mg for patients with severe strokes (treatment course--5 and 10 days).