In order to study the neurotoxic effect and the mechanism of fenvalerate and phoxim insecticides, rats were orally treated with fenvalerate (20 mg/kg BW), phoxim (160 mg/kgBW) and fenvalerate (20 mg/kgBW) plus phoxim (160 mg/kgBW). The glutamate (Glu) and gamma-aminobutyric acid(GABA) immunoreactive cells of the central nervous system of rats were observed by immunohistochemical method. The results showed that the total number, percentage of positive area and integral optical density of Glu immunoreactive cells in cerebral cortex, hippocampus and striate exhibited a characteristic decrease in the groups fed with fenvalerate and fenvalerate plus phoxim, while those of GABA were enhanced to certain extents. No obvious changes in Glu or GABA were observed in the phoxim group as compared with the controls, and no significant difference was observed between the fenvalerate group and the fenvalerate plus phoxim group. The results suggest that the disturbance of Glu and GABA metabolism may play an important role in the development of pyrethroid neurotoxicity, and there is no interaction between phoxim and fenvalerate pesticides on Glu and GABA activities.