Antiarrhythmic drugs, which are commonly used during out-of-hospital cardiac arrest, do not improve survival or favourable neurological outcomes. Investigators in the Resuscitation Outcomes Consortium randomly assigned 3,026 patients with nontraumatic out-of-hospital cardiac arrest and shock-refractory ventricular fibrillation or pulseless ventricular tachycardia to receive parenteral amiodarone, lidocaine, or saline placebo, in addition to standard care. Survival to hospital discharge was 24.4%, 23.7%, and 21.0% in each group, respectively. Neurological outcome at discharge from hospital was also similar in each group. Of note, administration of amiodarone or lidocaine seemed to be associated with a higher rate of survival compared with placebo when cardiac arrest was witness by a bystander, but not among those with unwitnessed cardiac arrest, perhaps indicating the importance of a fast response time and of bystander-initiated cardiopulmonary resuscitation.