The changes of oxygen exchange in tissues with the patients with chronic obstructive bronchitis (COB) of elderly (60 persons) and mature (20 persons) age, and also with practically healthy young (20 persons) and elderly (20 persons) people were investigated. The tissue oxygen tension was defined in the hypodermic fat of the left forearm by the polarographic method by Polarograph "LP-7" (Czechoslovakia) with functional tests with 10-minutes inhalation of oxygen and cross-clamping of the vessels of the left forearm during 10 minutes, that has allowed to characterize the major factors determining the oxygen exchange in tissues--delivery and consumption of oxygen. It was marked, that the changes of oxygen exchange in tissues with aging and with COB were unidirectional. The efficiency of this process is reduced, that leads to the development of tissue hypoxia. The intensity of tissue respiration decreases more evidently for the elderly COB patients in comparison with the COB patients of mature age.