The autopsy material was used for histological and histochemical study of lesions in tubules of the kidneys in chronic glomerulonephritis in comparison with those in acute renal insuffuciency (ARI) of various etiologies. In addition to the phenomena of intracellular regeneration in tubules of the functioning nephrons with formations of nephromas and tubule atrophy in the zone of glomerular sclerosis, some observations showed signs of insufficiency of cortical circulation. They were manifested in dystrophy of the proximal segment epithelium. Dystrophic changes are followed by regeneration which occurs at different times and runs an irregular course. Changes in the tubules are similar to those observed in the oligo-anuria stage of ARI. When cortical circulation is not compensated, paresis and collateral insufficiency develop. Small cortical necroses may be formed. All these changes, when they occur in extracapillary proliferation, may be manifested by the clinical symptocomplex of acute renal insufficiency.