During experimental glaucoma with diabetes in rabbits, in the filtering tissues of the eye, a state of oxidative stress is formed manifested by a significant decrease in the activity of antioxidant enzymes and the accumulation of products of free radical oxidation of lipids and proteins. Administration of a lipid-soluble form of vitamin B1 benfotiamine effectively reduced the manifestations of oxidative stress in the tissues of the anterior chamber of the animal eyes. This biologically active substance increased antioxidant capacity in tissues by activating antiradical protection enzymes: superoxide dismutase activity increased by 51%, catalase by 36% and glutathione peroxidase by 45% compared to the untreated animals. In addition, the processes of lipid peroxidation and oxidative destruction of protein molecules were decreased under the influence of benfotiamine. The level of malondialdehyde (MDA) was reduced by 47%, and the marker of oxidative damage to proteins of CO-groups by 35% relative to the untreated group. The results obtained may be a basis for further studies of the pharmacological substance benfotiamine in the clinic of glaucoma accompanied by diabetes, which will expand the arsenal of pathogenetically sound therapy of this serious disease.