This chapter reviews the most common psychiatric medications used in the emergency setting. It discusses the larger group of psychiatric medications one encounters daily on patients' medication lists. The most commonly prescribed psychiatric medications are the antidepressants, subdivided into four classes: tricyclic antidepressants (TCAs), heterocyclic antidepressants, selective serotonin reuptake inhibitors (SSRIs) and monoamine oxidase inhibitors (MAOIs). Antipsychotics, despite numerous side effects, have revolutionized the treatment of schizophrenia, allowing patients who once had to be hospitalized to live fairly normal lives. Several medications are considered mood stabilizers, also referred to as antimania medications. They include lithium, carbamazapine, valproic acid, and some atypical antipsychotics. Chemical restraint of an agitated patient is perhaps the most common reason psychiatric medications are used in the emergency department. The most common medications used for chemical restraint are haloperidol, droperidol, ziprasidone, olanzipine, lorazepam, and midazolam. The atypical antipsychotics are increasingly being used for acute agitation.