To study the sensitivity of some central brain structures to the action of an electromagnetic field of decimeter waves (EMF of DW) a dynamic investigation of single unit activity was undertaken. Neurons of the hippocampus and hypothalamus with an excitatory type of response were found to have the greatest reactivity to EMF of DW. Neurons of the mesencephalic reticular formation and of the specific nuclei of the thalamus had mostly an inhibitory type of response. The number of neurons responding actively to EMF of DW and the number of inactive neurons varied depending on the energy density of the EMF.