Nosocomial infection remains a significant consequence of hospitalization. Estimates are that from 3% to 5% of patients leave the hospital having acquired infection, depending on case mix, hospital size, and multiple other factors. Examination of the microbial etiology of these infections provides important information in day-to-day decision making in individual hospitals regarding potential outbreaks, unusual pathogens, antimicrobial resistance, and local trends in the etiology of infection. It is also useful periodically to examine trends in the etiology of infection over more prolonged time periods to detect shifts in the cause of infection. This report uses two sources of data, pooled data from participants in the National Nosocomial Infections Surveillance (NNIS) System of the Centers for Disease Control (CDC) and single hospital data from a large tertiary referral teaching hospital, the University of Michigan Hospital, to examine trends in etiology of hospitalacquired infection in the decade of the 1980s.