Localized stereotaxic lesions wereplaced in the pulvinar nuclear group of the cat thalamus, and the ensuing fiber degeneration was traced to the cerebral cortex by the method of Nauta and Gygax. The medial pulvinar nucleus (the major portion of nucleus lateralis pars posterior of Rioch) projects fibers to the banks, particularly the lateral, and fundus of the middle and posterior portion of the middle suprasylvian sulcus and the adjacent part of the posterior ectosylvian gyrus, and to the caudal bank of the posterior suprasylvian sulcus. The lateral pulvinar nucleus (pulvinar of Rioch) sends fibers to the crown and the medial and lateral sulcal lips of the middle and posterior suprasylvian gyri, the zone of confluence of the posterolateral and posterior suprasylvian gyri, and the medial cortex around the splenial sulcus including its fundus, area 19. The inferior pulvinar nucleus (nucleus posterior of Rioch) projects mainly to the medial bank of the lateral sulcus (area 19) and the medial bank of the middle suprasylvian sulcus (Clare-Bishop area). It also appears to send some fibers to the lateral bank of the lateral sulcus and parts of the convexities of the lateral and suprasylvian gyri. The supra-geniculate nucleus gives off fibers to the anterior sylvian gyrus and the adjoining posterior bank of the anterior ectosylvian sulcus, and probably to the cortex around the anterior half of the middle suprasylvian sulcus.