Structural and metabolic status and function of erythrocytes were studied in patients with chronic bronchitis, chronic inflammatory diseases of the upper airways, and chronic colitis. Complex study of the peripheral component of the erythron showed that disorders in erythrocyte morphology and function (decreased erythrocyte dry weight, low concentration of sulfhydryl groups and lipoproteins, decreased content of high molecular weight polypeptides in parallel with increased content of low molecular weight proteins, increased number of transformed cells, and enhanced reversible aggregation) were nonspecific and did not depend on the location of the inflammatory process.