Objective. To analyze specific changes in brain tissue of patients with idiopathic normal pressure hydrocephalus at cellular and subcellular levels. Material and methods. Brain biopsies from 32 patients with idiopathic normal pressure hydrocephalus were investigated by light and electron microscopy. Biopsies were made in 3 points (the cortex, subcortical and periventricular white matter during ventricular catheter positioning). Results. A number of pathological features of idiopathic normal pressure hydrocephalus were identified. Most frequent were the exhaustion of brain tissue, enlargement of perivascular spaces, aseptic necrosis, and amyloid and Lewy body’s formation. Conclusion. The changes in brain tissue of patients with idiopathic normal pressure hydrocephalus transform our views on its mechanisms. It becomes clear that idiopathic normal pressure hydrocephalus is part of common neurodegenerative process that has characteristic features affecting clinical manifestations of the disease.