Abstract: Objective：To study the effect of etomidate on GABAergic transmission in neurons of rat ventrolateral preoptic （VLPO）area. Methods：Rat ventrolateral preoptic area slices were prepared. Inhibitory postsynaptic current（IPSC）were investigated using whole-cell patch-clamp recording in VLPO neurons. Results：Etomidate（0.1 μmol/L）reversibly decreased the amplitude of evoked IPSC in VLPO neurons，without changing its paired-pulse ratio（PPR） . Etomidate（0.1μmol/L）decreased the frequency and amplitude of spontaneous IPSC，did not induce appreciable change in the kinetics of the spontaneous IPSC. Conclusion：Etomidate may act presynaptically and postsynaptically to suppress GABAergic transmission to VLPO neurons，this effect may excite these neurons，lead to the inhibition of histaminergic neurons in tuberomamillary nucleus，which will decrease releasing of histamine and result in anesthesia and sedation.