OBJECTIVE: To investigate the effect of monosodium glutamate (MSG) on the structure of the circumvallate papillae-von Ebner's salivary gland complex (CP/VEGs) and Remak's ganglion.   DESIGN: 5 different groups were created, (control group I) in which rats fed on regular diet, (group II) received 10g MSG/mixed with 100g basal diet daily, (group III) received 20g MSG with same route of administration; first 3 groups were sacrificed after 2 months, (group IV) received 10g MSG, (group V) received 20g MSG; but were sacrificed after 4 months. Histological structures of examined tissues of different groups were studied using H & E stain. In addition, immunohistochemical localization of S-100 protein was conducted.   RESULTS: Inflammation and degenerative changes were observed in the tissues of (CP/ VEGs) especially in taste buds, Remak's ganglion, nerves and salivary acini of different groups in comparison to control. The severity of such degeneration increased with higher doses for longer periods reaching peak in last group with complete degeneration of most of taste buds, ganglion cells, nerve fibers and acinar cells. Similar to this, immunohistochemistry demonstrated increased expression of S100 within tissues of taste buds, serous acini & ducts of experimental groups compared with control, but the opposite was true representing the Remak's ganglion and nerves.   CONCLUSIONS: MSG presented a dose-time dependent degenerative, inflammatory and neurotoxic effect on taste buds, Remak's ganglion and von Ebner's gland that endanger the sense of taste and salivary flow.