To investigate the glutamate-like immunoreactivity (Glu-IR) changes in inner hair cells (IHCs) of guinea pigs cochlear after noise exposure. Guinea pigs were distributed into 6 groups including control group (g1), and groups of immediately (g2), 8 hours (g3), 1 day (g4), 3 days (g5) and 7days (g6) after noise exposure. The experimental groups were exposed to 120 dBLp 1/3 octave 4 kHz narrow band noise for 4 hours to ruin the organ of Corti. The first turn of the organ of Corti was dissected to make ultrathin sections and under went immunoelectron study. The density of gold particles of Glu-IR in IHCs was measured. Results showed that Glu-IR in IHCs after noise exposure changed dynamically. The density of gold particle in IHCs of g2 significantly increased (p < 0.001) compared with gl and decreased in g3 (p < 0.001), whereas there were no significant difference in the groups of g4, g5 and g6 (p > 0.05). The results suggest that there may be glutamate autoreceptors in the membrane of IHCs and the glutamat To investigate the glutamate-like immunoreactivity (Glu-IR) changes in inner hair cells (IHCs) of guinea pigs cochlear after noise exposure. Guinea pigs were distributed into 6 groups including control group (g1), and groups of immediately 8 hours (g3), 1 day (g4), 3 days (g5) and 7 days (g6) after noise exposure. The experimental groups were exposed to 120 dBLp 1/3 octave 4 kHz narrow band noise for 4 hours to ruin the organ of Corti. The first turn of the organ of Corti was dissected to make ultrathin sections and under went immunoelectron study. The density of gold particles of Glu-IR in IHCs was measured. Results showing that Glu-IR in IHCs after noise exposure changed dynamically (P <0.001) compared with gl and decreased in g3 (p <0.001), there was no significant difference in the groups of g4, g5 and g6 (p> 0.05) The results suggest that there may be glutamate autoreceptors in the membrane of IHC s and the glutamat