The monograph is devoted to the problem of chronic obstructive pulmonary disease (COPD) and bronchial asthma (BA). Current state of the problem according to the data of the literature is described. The results of long-term cohort study, including 177 patients with COPD and BA are presented. With the help of modern statistical methods of analysis (univariate and multivariate) different factors and therapeutic effects influencing on the rate of decline in lung ventilation function in COPD and BA are identified. Investigation is carried out in accordance with international guidelines for conducting epidemiological studies STROBE.