AbstractTo determine the arrangement of projections in the somatic sensory nuclear region in the thalamus of sheep, microelectrodes were used to locate and map neural units and groups of units responding to mechanical stimulation of peripheral receptive fields in nine animals anesthetized with Dialurethane. Most of the sensory nuclear region (70–80%) contains projections from ipsilateral oral and perioral fields, Of this volume 16–25% (10–20% of the total) was responsive to stimulation of tissues inside the mouth. The ipsilateral projections are organized differently than are the meager projections from contralateral fields. The contralateral projections are ordered in the same general pattern seen in other mammalian thalami, with caudal fields represented laterally in the nucleus, rostral fields medially, axial fields and maxillary‐nasal fields dorsally, and limbs and mandibular fields ventrally. In the ipsilateral projections, however, mandibular external fields are represented dorsally, and maxillary and nasal fields more ventrally. Still more ventral are projections from the teeth and palate, and most ventral is the representation of the tongue. In all of the ipsilateral projections, the more ipsilateral fields (fathest from the rostral midline) are represented more medially in the thalamus. The exaggerated relative volume of thalamus responding to stimulation of oral and perioral surfaces may reflect the behavioral specialization of a grazing