The patient with a red eye constitutes a very common clinical problem encountered in the Emergency Department setting. Conjunctivitis, the most common cause of the red eye, generally is not associated with disturbance of vision or associated ocular pain. If either of these symptoms is present, a more serious disorder must be suspected. Treatment of infectious conjunctivitis is guided by interpretation of a Gram's stain and subsequent culture of any exudate present. Initial treatment of most cases includes use of topical antibiotic and local comfort measures. Complications of infectious conjunctivitis include more invasive disease such as keratitis or abscess formation, with potential corneal perforation and destruction. All patients should be referred for ophthalmologic followup, both to assess adequacy of treatment and to treat unexpected complications. Remember that allergic conjunctivitis is a common condition that responds to antihistamine decongestant medications given orally or topically. Occasionally these conditions are caused by self-prescribed use of ocular medication, and discontinuation of all eye medication is required. Corticosteroid eye drops are rarely indicated and should be used only at the direction of an ophthalmologist. When the diagnosis is uncertain, treatment is best withheld, as "shotgun" therapy is seldom beneficial.