Considering mainly practical aspects, a review of available methods of virological diagnosis of acute respiratory diseases is given. The first part contains the elements of virological diagnostics, especially a description and valuation of rapid detection of virus using fluorescent antibodies, and of haemadsorption technique for rapid diagnosis. Moreover, methods of viral isolation (cell cultures, embryonated eggs), conventional serological tests (CFR, HAIT, NT), and recent, not yet generally applied serological techniques (passive haemagglutination, indirect fluorescent antibody technique, haemadsorption inhibition test, radial immunodiffusion, radial immunohaemolysis, radio immune assay, enzyme linked immune assay) are described and valued as diagnostic tools in viral diseases of respiratory system. The second part deals with the specific diagnostics of infections by influenza, parainfluenza, RS-, adeno-, corona-, and rhinoviruses. Special instructions for the application of available tests and for the interpretation of results are given.