The nucleo-plasmic index was investigated in lizard dorsal root ganglion neurons from different spinal levels (cervical, thoracic, lumbar and caudal) in normal conditions, as well as in caudal dorsal root ganglion (DRG) neurons innervating the regenerated lizard tail (caudal hypertrophic ganglia). Results showed no statistically significant difference in the distribution of nucleo-plasmic index values in DRGs from different spinal levels providing sensory innervation to peripheral territories of different size. On the contrary, in the caudal hypertrophic ganglia, a significant shift towards lower values of the nucleo-plasmic index was observed. This observation suggests that this 'old', and merely morphological, parameter could be regarded as a good and simple marker for the study of neuronal hypertrophy considered as a dynamic response of neurons to variations of the innervation territory.