Aldicarb, a synthetic carbamate compound used as an insecticide and herbicide, is also employed as a pharmacological cholinergic agent in therapeutic forms. Inhibition of the enzyme AChE, which results in accumulation of ACh, is the basis for its use as an insecticide and it resulted in toxicity in a variety of animals including man. In this work, experiments were carried out in vitro and in vivo to study the effects of aldicarb on the activity of ChE enzyme extracted from whole and five different parts of rat brain, namely: basal ganglia, frontal cortex, medulla oblongata, pons and cerebellum. Kinetic measurements of Michaelis constants (Km), enzyme inhibitor dissociation constants (Ki) as well as the rate of carbamylation (k2c) and binding constants (Kl) for the inhibition of the enzyme obtained from the different parts were done. The carbamylation rate (degree of inhibition of AChE by carbamate) and binding constant for inhibition of whole and different parts of brain in vitro, indicated that the carbamylation rate constants of pons, medulla oblongata and cerebellum were higher than those of other parts. Inhibition of AChE in the different parts of the brain in vitro by aldicarb was of the competitive type, with different enzyme inhibitor dissociation constants (Ki). In vivo studies showed that the inhibition was marked in the enzyme obtained from pons, medulla oblongata and cerebellum; the parts responsible for vital centers and balance which coinsize with the in vitro results.