Transganglionic transport of horseradish peroxidase-wheat germ agglutinin conjugate (HRP-WGA) was used to study the somatotopic organization of pulpal afferent neurons innervating the different types of teeth in the trigeminal ganglion and trigeminal sensory nuclear complex (TSNC). In separate animals, the upper first 3 incisors (UI 1–3), canine (UC), second premolar (UP 2) and third premolar (UP 3), and the lower first three incisors (LI 1–3), canine (LC), first premolar (LP 1), second premolar (LP 2) and molar (LM) were traced in this experiment. Cell bodies innervating posterior teeth were found with greater frequency in dorsal maxillary ganglion regions, while somata supplying more anterior teeth were predominant ventrally. In contrast, cell bodies innervating the lower teeth were not arranged in a somatotopic fashion in the mandibular subdivision. Each pulpal afferent from lower and upper teeth projected to the subnucleus dorsalis (Vpd) of the pars principalis, the rostrodorsomedial (Vo.r) and dorsomedial parts (Vo.dm) of the pars oralis (Vo), the medial regions of the pars interpolaris (Vi), and laminae I, II, and V of the medullary dorsal horn, and terminal fields between the upper and lower teeth were separated in each subdivision. Pulpal projections from both the upper and lower teeth to each subdivision were organized in a somatotopic manner, while an extensive overlap in projections was noted between the adjoining teeth. In the Vpd, the upper and lower teeth were represented dorsoventrally, and projections from the anterior to posterior teeth in the upper jaw were arranged in both rostrocaudal and ventrodorsal sequences whereas those in the lower jaw were organized caudarostrally and lateromedially. In the Vo.r and Vo.dm., the upper and lower teeth were represented in a mediolateral sequence and projections from the anterior to posterior teeth were organized in a ventrolateral to dorsomedial sequence. In the Vi, pulpal projections were organized in a topographic fashion similar to that observed in the Vo.r and Vo.dm. In the medullary dorsal horn, the upper and lower teeth were represented in laminae I, II and V in a lateromedial sequence. Their projections to laminae I and V were topographically organized in a mediolateral and rostrocaudal sequence. In a mediolateral sequence, the projection of upper teeth was arranged mediolaterally from the posterior to anterior teeth, whereas the lower teeth were represented in a lateromedial fashion inverse to the arrangement of the upper teeth. In a rostrocaudal sequence, terminal fields from all the teeth appeared rostrally, but its rostrocaudal extent differed among the teeth in that the neurons innervating more posterior teeth terminated in progressively more caudal levels. The above results suggest that the rostrocaudal somatotopic arrangement of the teeth is compatible with an onion-skin organization while the somatotopic organization of the teeth in other subdivisions of the TSNC should be represented in a manner that is independent of the generally accepted homuncular map in the form of an inverted face.