The red eye is one of the most frequent presenting complaints in the emergency department setting. A wide spectrum of disease processes may present as a red eye, ranging from benign self-limiting etiologies to serious vision-threatening ones. The emergency physician must be adept at recognizing "red flags" from the history and physical examination that necessitate immediate treatment and referral. In addition, it is imperative for the emergency physician to recognize the need for immediate versus elective ophthalmologist consultation for the various conditions. This article includes a discussion of the key historical features, clinical presentations, physical examination findings, and management of the more common causes of the red eye.