Abstract The distribution of the glial cells in the pulmonate gastropod Megalobulimus oblongus was studied by means of an immunohistochemical procedure. These cells expressed glial fibrillary acidic protein in their cell bodies as well as in their processes. In all ganglia of the central nervous system, four types of glial cells were identified. The glial lacunar network and the perineuronal glial cells were found in the cortical region of the ganglia, and the perisynaptic and the fibrous glial cells in the neuropilar region. However, in the procerebrum of the cerebral ganglion the glial cells only had a reticular distribution throughout the cellular area. These observations provide morphological evidence of glial cell functions. These cells are probably involved in the support of neurones, the uptake and/or degradation of neurotransmitters, the transfer of metabolic substrates to neurones, as well as the regulation of ionic constituents of extracellular space. As occurs in vertebrates, there is a strong relationship between the different cellular components of the central nervous system of this invertebrate.