Reorganization of background electric activity of newborns brain under the action of rhythmic photostimulation was studied in children of the first month of life in a state of quiet alertness by the method of age transversal slides (I, II, III-IV weeks of life). At the age of III-IV weeks, the repeated rhythmic light stimulation elicits a stable reorganization of the background activity in the theta-frequency range in the central areas at 5 Hz stimulation and in delta-frequency range in the occipital areas at 2 Hz stimulation. Characteristics of spatial manifestation of background activity reorganization in various cortical areas reflect frequency-specific character of newborns' cerebral cortex reactivity, appearing to the end of the first month of postnatal development.