The objective of the present study was to analyse the available data on the qualitative and quantitative composition of nasal secretion (NS) obtained from the healthy subjects and the patients presenting with various diseases of the nose and paranasal sinuses (PHS). The author maintains that investigations for the identification of organic and inorganic components contained in the nasal secretion and for the measurement of their contents as well as the studies of its properties with the use of the biochemical and physical methods are of primary diagnostic and prognostic importance. It is supposed that the physical properties of NS can be described in terms of the notions and principles of rheology. i.e. the science of the flow of matter. For this reason, airway secretion plays an important role in the functioning of the respiratory organs and the maintenance of homeostasis of the internal environment of the body. The composition of secretion from the nasal cavity and paranasal sinuses is considered to be a factor of of pathogenesis and indicator of the pathological processes in the respiratory tract. It is recommended that the adequate mucolytic medicines should be included into the treatment protocol of PNS diseases to liquefy the thick pus and viscous secretion in order to improve the mucociliary clearance and facilitate the release of secretion from the sinuses.