Calcium chloride has been advocated since the 1920s for resuscitation of asystole and ventricular fibrillation. Most reports have been anecdotal, and have failed to substantiate its effectiveness. In two large retrospective series with a collective experience of 181 patients, investigators reviewed the effectiveness of calcium chloride in asystole and did not support its use. A prospective, randomized, double-blind study comparing calcium chloride with saline in the prehospital setting was done. Patients with trauma or pediatric arrests were excluded. During the period from October 1982 to October 1983, a total of 32 patients with witnessed arrests presented with a rhythm of asystole and were refractory to epinephrine, bicarbonate, and atropine. The rate of successful resuscitation in the calcium group was 5.6% (1/18), and there were no successful resuscitations (0/14) in the saline group (P = .37). A successful resuscitation was defined as conveyance of a patient with a rhythm and pulse to an emergency department. Groups were analyzed for sex, age, cardiac history, and cardiac drugs, and there were no statistically significant differences. No patient who was successfully resuscitated in the field was discharged alive from the hospital. Calcium chloride is of no value in resuscitating refractory asystole in the prehospital cardiac arrest setting.