Background/Objectives: Endoscopic diagnostics and therapeutics increasingly are replacing invasive surgical procedures and are being performed in ambulatory and inpatient settings. Cleaning and disinfection of endoscopes and their accessories is complex and must be performed according to U. S. Food and Drug Administration (FDA) labeling and manufacturer instructions. Breaches in endoscope reprocessing can expose patients to viral and bacterial pathogens andmust be addressed on a case-by-case basis. Infection preventionists (IPs) play a fundamental role in identifying and investigating such breaches. State health departments have an expanding role in healthcare-associated infection prevention and consultation separate from regulatory functions. We discuss a state health department infectious disease epidemiology program's experience of providing public health consultation to guide the investigation of endoscope reprocessing breaches. Methods: Over the past 18 months, IPs from several healthcare facilities requested assistance after identifying incidents of inadequate endoscope reprocessing. In each situation, IPs collected information on the nature of the breach, facility type, clinical practices, endoscope/endoscopic accessories used, and cleaning/ disinfection procedures. In consultation with Centers for Disease Control and Prevention (CDC), the risk to patients, including pathogen transmission, was evaluated. Interventions such as patient notification, internal facility communication, and FDA notification were assessed and implemented as appropriate. Results: From 5/2010-9/2011, 7 endoscope reprocessing breaches were reported from 5 healthcare facilities (1 clinic, 1 ambulatory surgical center, 3 hospitals) and involved various endoscope types (upper GI endoscope [3], cystoscope [1], hysteroscope [1], colonoscope [1], transesophageal echocardiography scope [1]). Breaches were recognized by technicians (blood in the scope after reprocessing, scope occlusion due to broken accessory piece) or by IPs (cluster of bacterial infections post-endoscopic procedure, observation/audit of technician practices). These incidents resulted from incorrect use of endoscopic accessories, reprocessing of single use devices, or failure to follow FDA labeling and/or manufacturer reprocessing instructions. Four breaches were reported to FDA because the manufacturer and/or vendor representative provided incorrect instructions. To assist future breaches, we developed an endoscope breach assessment tool and list of resources. Conclusions: IPs associated with healthcare facilities where endoscopic procedures are performed should be familiar with national endoscope reprocessing guidelines. Reprocessing protocols and procedures must be assessed regularly, particularly when implementing equipment or procedure changes, and all staff involved with endoscopic procedures and/or reprocessing must receive regular education, training, and competency testing. State health departments should also be aware of national endoscope reprocessing guidelines and other resources in order to assist healthcare facilities in investigating breaches, including notifying patients, and reporting to FDA. IPs should be aware that the