The objectives of this guidance document are to: 1) highlight the cross-contamination risk associated with specific types of irrigation valves and accessories when used with flexible gastrointestinal endoscopes; 2) clarify terminology used to describe these devices; and 3) outline strategies to mitigate the risk of cross-contamination between patients. Flexible gastrointestinal endoscopes and accessories (including valves and other devices used for irrigation) are Class II devices, as described in 21 CFR 876.1500. FDA uses product codes to identify devices that supply endoscopic irrigation, the most common being FDF (colonoscope and accessories, flexible/rigid), FDS (gastroscope and accessories, flexible/rigid), and OCX (endoscopic irrigation/suction system). These irrigation devices may be submitted to FDA in premarket notification (510(k)) applications as part of a flexible gastrointestinal endoscope system or separately as accessories to flexible gastrointestinal endoscopes.