The routine sampling of environmental surfaces within a healthcare facility is generally not recommended by the Centers for Disease Control and Prevention (CDC), the Association for the Advancement of Medical Instrumentation (AAMI), and several other healthcare organizations. There are a few circumstances, however, for which some organizations do recommend this practice. For instance, the CDC and the Association for Professionals in Infection Control and Epidemiology (APIC) recommend environmental sampling as clinically required during an outbreak investigation. The CDC and AAMI also recommend routine sampling of the rinse water used during hemodialyzer (but not endoscope) reprocessing. The rationale for this recommendation is based in part on reports of pyrogenic responses, patient infections, and bacteremia due to waterborne, gram-negative bacteria during hemodialysis. To determine whether the basis for this rationale might similarly apply to the rinse water used during endoscope reprocessing, the Food and Drug Administration's medical device reporting database, the endoscope reprocessing literature, and other sources were reviewed. The results of this review indicate that nosocomial outbreaks linked to endoscopes contaminated with gram-negative bacteria have been frequently reported. As a result, for several reasons, including to minimize the risk of patient infection due to gram-negative bacteria following endoscopy, this article recommends routine microbiologic sampling of the rinse water used during endoscope reprocessing.