In this study we tested the immunohistochemical reactions of various markers for the enteric nervous system in whole-mount preparations of the human colon. For that purpose we used polyclonal antibodies against the neuronal markers--protein gene product 9.5 (PGP), neuron-specific enolase (NSE), neurofilament protein 200 (NFP), microtubule-associated proteins (MAPs); and the glial markers--S-100 protein and glial fibrillary acidic protein (GFAP) for the immunoperoxidase reaction. Whole-mount preparations are more suitable for histopathological evaluation and interpretation than sections, because the enteric nervous system consists of three-dimensional plexuses lying within the layers of the intestinal wall. Sections show only a part of the plexuses, neurons and glial cells. On the other hand, whole-mount preparations reveal the morphology of the plexuses as a whole. Among the neuronal and glial markers used, S-100 protein, the neurofilament protein, and the protein gene product 9.5 (PGP) produced the best results. Furthermore, this developing method provides new possibilities for the histopathological analysis of defects in the enteric nervous system, such as neuronal intestinal dysplasia (NID).