Respiratory viruses are a common cause of morbidity in childhood. Except in the child with immunodeficiency, the common respiratory viruses rarely pose a serious threat to life. Because infection with most of these viruses in childhood is nearly universal and usually bestows partial immunity, the "childhood respiratory viruses" are not generally thought of as being a cause of disease in adults. However, adults who work around children, who are frequently exposed to other adults and children with respiratory tract infections (as in a hospital clinic setting), or who are military recruits appear to be at risk of infection or reinfection with one of these agents. In addition, adults with immune deficiency are at a significant risk for serious infection. The risk of serious disease can be reduced by maximizing immunity with (re)immunization and optimal treatment of any underlying disorders. Tobacco smoke and respiratory irritants should be avoided and adults at risk for severe disease should avoid contact with infected children and adults as much as possible. Specific chemotherapy for viral pneumonia, when available, may reduce morbidity in selected individuals.