In order to locate the source of oxytocic activity in toad''s brain, the oxytocic activity of the following parts were studied brain hemispheres, di-encephalon, hypophyseal neurointermediate lobe, adenohypophysis, choroid plexus of 3d and 4th ventricle and brain stem. Only the neuro-intermediate lobe showed oxytocic activity in all the experiments. Neurosecretory material in the hypothalamus stained selectively with chrome hematoxylinphloxine of Gomori. The third ventricle choroid plexus showed CH positive granules in the epithelial cells, and extracts of this had oxytocic activity. Both the granules and the oxytocic activity disappeared when sexual activity began. It was concluded that the oxytocic activity resided in the neurosecretory granules.