Emergency physicians regularly encounter agitated patients. In extremely agitated and violent patients, the onset of many traditional medications is relatively slow and often requires additional medication. Ketamine is frequently used in emergency departments (EDs) for procedural sedation and intubation, but has recently been suggested as a treatment for acute agitation.We sought to examine the use of ketamine in the treatment of acute agitation in an ED setting, including vital sign changes as a result of this medication.This is a structured review of an historical cohort of patients over 7 years at two university EDs. Patients were included if they received ketamine as treatment for acute agitation. Abstracted data included age, vital signs including hypoxia, any additional medications for agitation, and alcohol/drug intoxication.Ketamine was administered for agitation on 32 visits involving 27 patients. Preadministration systolic blood pressure was 131 ± 20 mm Hg, with an average postadministration increase of 17 ± 25 mm Hg. The average baseline heart rate was 98 ± 23 beats/min, with an average increase of 8 ± 17 beats/min. No patients became hypoxic; 62.5% of patients required additional calming medication. Alcohol or drug intoxication was present in 40.6% of patients.We found ketamine was used rarely, but had few major adverse effects on vital signs even in a population with 21.9% alcohol intoxication. However, a high proportion (62.5%) of patients required additional pharmacologic treatment for agitation, implying that administering ketamine is useful only for initial control of severe agitation.