The article deals with research into bronchial asthma and diabetes mellitus as its complication with respect to genetic approach. It has been shown, that bronchial asthm a was characterized by the complete set of features specific for multifactor diseases. Correlations between bronchial asthma and diabetes mellitus as its complication are being studied now. Basing on a study of a large diabetic population in Moscow, data concerning bronchial asthma incidence among them have been obtained. The findings have been compared to current epidemiological data on bronchial asthma incidence in various regions of the USSR. Further steps have been outlined to examine families of probands with bronchial asthma and diabetes mellitus to decide upon distinguishing high risk groups among probands — in respect to steroid administration; among relatives of the 1st order of relation — in respect to possible development of multifactor diseases; primary preventive activities among population.