Study objective: Parenteral benzodiazepines or antipsychotics are often used to manage acute agitation in emergency department (ED) settings in which alternative strategies have failed or are not feasible. There are scant data comparing parenteral medication regimens. We aim to determine the efficacy and safety of intravenous droperidol or olanzapine as an adjunct to intravenous midazolam for rapid patient sedation. Methods: We undertook a randomized, double-blind, placebo-controlled, double-dummy, clinical trial in 3 EDs (August 2009 to March 2011). Adult patients (n=336) requiring intravenous drug sedation for acute agitation were randomized to receive a saline solution (control), droperidol (5 mg), or olanzapine (5 mg) bolus. This was immediately followed by incremental intravenous midazolam boluses (2.5 to 5 mg) until sedation was achieved. The primary outcome was time to sedation. Secondary outcomes were need for rescue drugs and adverse events.