Unlike most animals, birds are blessed by an air sac system that essentially provides the endoscopist with a preinsufflated patient. Thanks to this unique anatomy and the pioneering work of Greg Harrison, Michael Taylor, and other avian veterinarians, rigid endoscopy has enjoyed considerable popularity in avian practice over the past 30 years. Indeed, endoscopy now is considered an essential component of the avian investigation for many clinical presentations, and indeed few could argue that high-quality avian medicine is possible without rigid endoscopy. The ability to examine the internal viscera, respiratory, gastrointestinal, and reproductive tracts, and collect samples for definitive diagnosis continues to play a central role in avian practice, and this article summarizes the most common diagnostic endoscopic approaches likely to be undertaken in companion species.