Flexible fiber-optic endoscopes are widely used in the United States for diagnostic and therapeutic procedures. Between uses, endoscopes should be cleaned and disinfected either manually or by using automated machines. However, outbreaks have occurred among patients exposed to contaminated endoscopes or to inadequately disinfected bronchoscopes (1-4). This report summarizes one outbreak of nosocomially acquired infection (Wisconsin) and one of pseudoinfection (Missouri) linked to endoscopes contaminated during cleaning and disinfection by automated reprocessing machines.