Using transmission electron microscopy, erythrocyte ultrastructure in norm and pathology was described. Among the morphological phenomena, most common were local and extensive erythrocyte plasmalemmal defects in the form of its loosening, thinning, consolidation and thickening, rupture, fragmentation, exfoliation from stroma with the formation of cavities. Plasmalemmal destruction may be accompanied with the formation of micro- and macroexovesicles, some of which lose the connection with the erythrocyte. Morphological signs of erythrocyte stromal disorganization included irregular distribution of hemoglobin granules with the formation of the regions of increased and decreased electron density, loosening of the internal structure up to the formation of cavities, as well as endovesicles, partially containing small or large osmiophilic particles. It was shown that in pathological processes of different genesis (malignant tumors, chronic bronchitis, burn trauma, schizophrenia) ultrastructural changes of erythrocytes have typical character.