A study was designed to determine the incidence of atypical or geriatric presentation of infection in a long-term-care-hospital population of aged veterans. During the 6-month period of surveillance there were 65 instances of functional decline among the 143 veterans, with 50 episodes of infection. Although the symptoms and signs of infection were attenuated in many patients, a diagnosis was reached by careful examination and investigation. The majority of patients had a temperature of at least 38 degrees C in the presence of infection and it is concluded that the afebrile response to infection is rare in this population. During the course of this study the death rate in this institution dropped to about half of what was anticipated, and returned to previous levels following completion of the study. Infection can be recognized at a very early stage despite an atypical geriatric presentation and early treatment reduces morbidity and mortality.