Pseudoexfoliation syndrome (PEX Sy) presents a continual challenge to the ophthalmologists because of its unknown etiopathogenesis and development of aggressive glaucoma and some complications of the cataract surgery. Contemporary hypothesis focus oxidative stress as a clue event in the ageing process, as well as in age-related cataract genesis. Frequencies of the secondary ageing diseases were investigated in 162 patients with age-related cataract and 55 age and sex matched control subjects, and some elements of the oxidative stress-antioxidation protection and the lipid peroxidation products in their serums. Similar parameters of oxidative stress were also analyzed in 80 samples of humour aqueous and corticonuclear lens' blocks, and compared according to the different secondary ageing diseases appurtenance (diabetes mellitus, atherosclerosis, obstructive pulmonary diseases etc.), also including PEX Sy. Examined influence of secondary ageing factors and PEX Sy on the age-related cataractogenesis by logistic regression showed the highest odds ratio for the PEX Sy(OR=4,516; p<0,05). Among investigated antioxidant elements (vitamins C and E, peroxidasis, GSH, catalase, albumin, %iMDA) in serums, catalytic activity of catalase shows significantly lower values in patients with PEX Sy(p<0,05). Antioxidant defense of humour aqueous, expressed as rate of induced malondialdehyde (%iMDA), and total sulfhydryle groups in the lens' corticonuclear blocks (TSH) have a lower values, whereas contents of lipid peroxides (LP) shows to a higher degree of the peroxidation in patients with PEX Sy, similar to the findings in patients with cataract and other diseases of the secondary senium. Changes on the corneal endothelium, in the anterior chamber angle, iris and lens, at the presence of the PEX Sy, in some extent respond to the hasten ageing. Findings considering the antioxidative defense and lipid peroxidation, point to possibility that, at least part of pathogenesis of ocular alterations with PEX Sy, appears due to higher oxidative stress. Lower activity of catalase may suggest to the liver function examinations, with the aim of investigation of the PEX Sy nature.