Abstract: Objective To explore the acute toxic mechanism of methyl tertiary butylether(M T BE),in the cerebellar cortex by detecting the change of the neuro transmitter C-amino-but yric acid(GABA).Methods 54 adult SD rats were randomly divided into control and eight experiment groups.The MTBE exposed doses were 700,1 050,1 400mg/(kg·bw) and the control group was used normal saline 1 400 mg/(kg·bw)respect ively injected by abdo minal cavity.Then the relative grey value of GABA expressio n was mensurated after exposed MTBE in 0.5,1.0,2.0,4.0,8.0 h in cer ebellar cortex.Results The expression of the GABA in cerebellar cortex was inceased when exposed MTBE700,1 050,1 400 mg/(kg·bw).The expression of the GABA in cerebellar cortex was changed in the different time(0.5,1.0,2.0,4.0,8.0 h)after being exposed to M T BE(1 050 mg/(kg·bw)).T he expression of the GABA began to increase in 0.5 h,reached peak in 1.0 h,began to reduce in 2.0 h,and was recovered to normal level in 8.0 h.Conclusion The acute toxic effect of MT BE in central nervous system is relevant to the neurotransmitter GABA.