The effect of acute intoxication by lindane on the AChE activity in blood plasma and in crude synaptosomal fractions from six CNS areas of rats has been studied. The effect of sodium pentobarbital on the convulsive syndrome caused by the above organochlorine compound is also presented. The joint administration of sodium pentobarbital together with lindane prevented the convulsive reaction which had been produced by lindane alone. In the animals intoxicated by lindane a general increase in the AChE activity both in plasma and in the CNS areas studied has been observed. The combination of sodium pentobarbital and lindane produced a decrease in the AChE activity in all the studied areas with the single exception of the spinal cord. These results are discussed bearing in mind the possible interaction between the GABAergic and cholinergic neurotransmission systems in the CNS.