Viral infections cause many diseases in the mucous membranes, the upper respiratory and digestive tract, the salivary glands and the ear.Recent advances in the pathogenesis of viral diseases brought about an increasing interest of otolaryngologists.The general part of this paper presents the fundamental properties of viruses, their structure and replication, and the pathogenesis of the different forms of viral infections.The section of viral diagnosis describes laboratory methods and their limits as well as the clinical interpretation of viral tests.An overview of prophylaxis and therapy of viral infections is given.The specialized section of the paper describes viral infections important for the otorhinolaryngologist. It includes infections of the aero-digestive tract, the ear and the salivary glands.Because of its special importance, Epstein-Barr virus and its associated diseases, and hypotheses about the oncogenesis of EBV -correlated tumours are presented in detail.The topic of the third part is the actual knowledge about interferon and its antiviral and antitumour effects. The findings of important clinical studies are discussed.The last chapter concerns with virushepatitis.Zusammenfassung. Virale Infektionen sind die Ursache einer Vielzahl von Erkrankungen im Bereich der Schleimhiiute des oberen Respirations-und Digestionstraktes, der Speiche1driisen und des Ohres.Neue Erkenntnisse der letzten Jahre tiber die Pathogenese viraler Erkrankungen fiihren zum wachsenden Interesse des HNO-Facharztes an deren Diagnostik und Therapie.Der allgemeine Teil dieses Referates macht mit wichtigen virologischen Grundlagen vertraut:Es wird auf die Struktur und die Vermehrung der Viren eingegangen sowie
