Infraslow oscillations (8 cycles per minute, 0.5–1 mv) formerly revealed in the rabbit's brain cortex, were also registered in the premammillary hypothalamus. This infraslow rhythm was absent in the thalamic nuclei of intact animal, but could be revealed after acting upon the brain metabolism by strichnine or atropine. Electric stimulation of hypothalamic dorsal-medial and ventral-medial nuclei increases the amplitude and the regularity of the infraslow rhythm in the sensomotor brain cortex and the hypothalamus proper. After strychnine injection the intensification of the infraslow fluctuations appears in the hypothalamus 10–30 minutes earlier than in the brain cortex. Prolonged stimulation of hypothalamus may cause generalized infraslow oscillations synchronic in different protions of the brain. Creating a definite gradient of electric field in the brain cortex the infraslow potential affects the excitalility of neurons, reflecting the association between the neuroendocrine function and the electric activity of the brain. Infraslow oscillations are one of the links in the integrative brain activity.