The labyrinthine reflex is influenced by changes of head position. To elucidate the anatomical pathway involved in this reflex, the author studied the afferent route by the retrograde WGA-HRP method in cats. After the injection of HRP into either the dorsal or the ventral Deiters nucleus, labeled neurons were investigated in the spinal cord, cerebellum, contralateral vestibular nucleus complex and brain stem nucleus.1) When WGA-HRP was injected into the dorsal Deiters nucleus, labeled neurons in the spinal cord were found mainly extending from the cervical to the lumbosacral spinal cord. A number of labeled cells were located predominantly contralaterally in the cervical segments, while a small number of labeled cells were found ipsilaterally in the lumbosacral segments. In the case of the ventral Deiters nucleus, labeled neurons were found extending from the cervical to the upper thoracic cord. Localization of la-beled neurons in the spinal cord was limited mainly to Rexeds laminae VII, VIlI.2) When WGA-HRP was injected into the dorsal Deiters nucleus, Purkinje cells were labeled in the cerebellar cortex. Most of them were restricted to the anterior lobe vermis ipsilaterally. In the case of the ventral Deiters nucleus, labeled neurons were found in the fastigi nucleus. Most of them were localized in the rostral region contralaterally.3) When WGA-HRP was injected into the dorsal Deiters nucleus, no labeled neurons were found in the contralateral vestibular nucleus complex. In the case of the ventral Deiters nucleus, a few labeled neurons were found in the superior, medial, descending and ventral Deiters nucleus.4) When WGA-HRP was injected into the dorsal Deiters nucleus, labeled neurons in the brain stem nucleus were found in the lateral reticular nucleus, the inferior olive nucleus and the external cuneate nucleus, while a small number of labeled cells in the lateral reticular nucleus and the external cuneate nucleus were ipsilateral only. Labeled cells in the inferior olive nucleus were present contralaterally. In the case of the ventral Deiters nucleus, labeled neurons were found in the nucleus reticularis gigantocellularis, although a few labeled cells ware present contralaterally.These results suggest that Deiters nucleus may be functionally divided into two parts, dorsal and ventral. In addition, afferents to Deiters nucleus are considered to be closely related to the control of posture.