An understanding of neuronal physiology at the single unit level requires knowledge of the functional properties of the neurons as well as a detailed description of its morphology. A full morphological description should include a three-dimensional (3-D) analysis. In this paper, we describe for the first time, 3-D morphology of individual neurons of the peripheral autonomic nervous system intact within whole-mount preparations. Neurons were filled with the fluorescent dye Lucifer Yellow and imaged by laser scanning confocal microscopy. Three- dimensional reconstructions were obtained using volume rendering methods on a set of serial optical sections obtained for each neuron. The 3-D images of the neurons we studied showed a complexity of shape and detail that is not readily apparent from images viewed by traditional microscopy.