It was found that the indicators of the function of external respiration are objective information about the physiology of respiration in healthy people, and are also useful for detecting early signs of hemodynamic disorders in patients with cardiovascular pathology and choosing appropriate therapy. Of particular interest is the problem of age-related changes in the parameters of the function of external respiration in healthy people and the question of the presence of the rhythm of daily fluctuations of these indicators in the norm and pathology of the cardiovascular and bronchopulmonary systems. In the works of G.L. Khasis (1970,1975), an increase in the frequency of breathing (BH) and minute volume of respiration (MVR) was found in healthy men and women in the evening without analyzing the indicators of FER at night. The results of this author's research indicated a tendency to decrease the MVR, maximum lung ventilation (MLV), respiratory reserve (RR), inhalation and exhalation power during physiological aging. Oxygen uptake in 1 minute (PO2) in men under 40 years of age turned out to be stable, and in older people PO2 is significantly reduced, starting from the morning hours. The oxygen utilization coefficient (CUO2) was relatively stable in individuals of different age groups. VS. Kokin (1967) revealed patterns of fluctuations in pneumotachometric indicators, which the author associated with changes in bronchial patency conditions, depending on the state of the autonomic nervous system at different times of the day. The analysis of the literature data indicates that the study of the indicators of the function of external respiration from chronobiological positions was not carried out systematically enough and the obtained results of studies of FER in healthy people of different ages are diverse and contradictory.