The complex nervous networks found throughout the mammalian gut—the enteric nervous system—are histologically, ultrastructurally, and, to some extent, functionally—similar to the central nervous system^1–3. The glial cells of the small enteric ganglia are generally classified as Schwann or satellite cells, since they are found in the peripheral nervous system, possess nuclei which ultrastructurally resemble those of Schwann cells and are derived from the neural crest^4,5. However, it has been argued that these cells resemble astrocytes of the central nervous system with respect to gross and fine structure, and their relationship with the enteric neurones and their processes^1,6. In immuno-histochemical studies of these cells, both in frozen sections of gut wall and in tissue culture preparations of the enteric plexuses, we found evidence that the enteric glial cells are rich in glial fibrillary acidic protein (GFAP), a protein associated with the 100 Å glial intermediate filaments⁷, and hitherto believed to be specific to astrocytes of the central nervous system only^8,9.