Acetylcholinesterase (AChE) activity and parameters of the system of regulation of lipid peroxidation (LPO) were estimated in blood of patients with Alzheimer's disease (AD) during therapy with amiridine and gliatiline. It was found that the therapy was accompanied by inhibition of AChE activity. A significant correlation was observed between clinical efficiency and changes of AChE activity. AD was characterised by essential changes in LPO parameters: the level of the primary products of oxidation was increased three times with a sharp increase (seven times) of total unsaturation of lipids. A significant correlation was found between AChE activity and the level of the primary products of oxidation in blood erythrocytes of AD patients before and after therapy with amiridine and gliatiline.