Adenoviruses are human pathogens that commonly infect the respiratory and gastrointestinal tracts. Adenovirus infections are endemic, particularly among children, but also may cause epidemics of pharyngoconjunctival fever, keratoconjunctivitis, gastroenteritis, and acute respiratory disease (ARD) among military trainees. Outbreaks of ARD among adults in the civilian sector are rare. In March 1997, an outbreak of acute respiratory disease (ARD) caused by adenovirus serotype 11 occurred among students at a job training facility in South Dakota. This report summarizes the epidemiologic and clinical features of this outbreak and discusses the change in availability of adenovirus vaccines for military use.