Qualitative evaluation and quantitative determination of antibody to respiratory pathogens represents a substantial part of research and applied virology. These investigations can serve quite different purposes. Epidemiologists need the serological data necessary for the control of influenza and other respiratory infections and for elucidating aetiological peculiarities of past infections. A system of constant surveillance of influenza morbidity and seroepidemiological status of the population has been organized in the USSR. The herd immunity is assessed as to circulating influenza viruses and some older strains which have gone out of circulation. The results obtained are important not only for current epidemiological analysis, but also because they enable the prognosis, to some extent, of the epidemic process, the evaluation of danger in shift of influenza viruses when their reappearance in the circulation is anticipated, as was the case in 1976 in the USA and in 1977 in China and in the USSR.Specialists who are developing new vaccines or improving existing ones are interested in determining the immunological status of those vaccinated. These results are essential for immunologists in order to elucidate mechanisms of humoral immunity. Based on serological information, the impact of chemoprophylactic and chemotherapeutic drugs on the immunological system can be evaluated. Determination of immune response to an infectious agent contributes essentially to a reliable diagnosis; as a result, the improvement of serological techniques is perpetuated in further investigations. It goes without saying that neither a single technique nor even a limited number of them can provide a solution to all the problems mentioned above.The purpose of this review is consideration of the main serological techniques available and their application in serological investigations of acute respiratory infections.