OBJECTIVE: To ascertain current infection control practices, endoscope cleaning procedures, perceived risks of infection, and implementation of universal precautions in gastrointestinal endoscopy units in the United States. DESIGN: National mailed survey of gastroenterology nurses and associates conducted anonymously in March 1988. SETTING: Completed surveys were received from all 50 states and Puerto Rico and from all practice settings. The most common practice setting was private/community hospitals (66%). PARTICIPANTS: Of the 4,952 survey forms mailed to all members and to interested non-members of the Society of Gastrointestinal Nurses and Associates, 2,158 (44%) were returned and 2,030 (41%) were completed and evaluable. Of the respondents, 1,487 (73%) were registered nurses. RESULTS: Sixty-seven percent (n = 1,358) of the respondents routinely used an enzymatic cleaner as a step in the instrument decontamination process; 93% (n = 1,879) chemically disinfected instruments after each case; and 88% (n = 1,779) disinfected endoscopes with an aqueous glutaraldehyde product. Respondents reported that they and a significantly smaller proportion of physicians (p < .001) employed barrier precautions for all endoscopic cases involving possible contact with blood/body fluids of patients known (66% versus 57%, respectively) and not known (12% versus 8%, respectively) to have a bloodborne infection. Endoscopy-related infections, usually bacterial, were reported to have occurred at their institutions by 6% (n = 116) of respondents. CONCLUSIONS: We conclude that cleaning, disinfection, and sterilization procedures for gastrointestinal endoscopic instruments vary, that appropriate protective apparel is not always worn, and that some practices may lead to preventable endoscopy-related infection in patients.