Bretylium tosylate is recommended by the American Heart Association Standards for Advanced Cardiac Life Support for refractory ventricular fibrillation after countershock, sodium bicarbonate, and epinephrine. According to this protocol, paramedics gave five to six milligrams per kilogram of intravenous bretylium by bolus in 96 patients with refractory fibrillation over a 24-month period. A positive response was defined as the presence of a palpable pulse following bretylium and countershock. Thirty-five percent of patients (34/96) responded following bretylium. Twenty-one percent (20/96) responded only temporarily with a rhythm and pulse. Fifteen percent (14/96) maintained a stable rhythm and vital signs on admission to the hospital, but only five patients, 5% of the total population, (5/96), were eventually discharged home. Clinical variables were similar in non-responders, temporary responders, and those admitted, but the times from the onset of Advanced Cardiac Life Support to receiving bretylium were 23.5 min, 20.3 min, and 14.3 min respectively. We conclude that about one-third of patients in refractory ventricular fibrillation respond following bretylium and countershock and that earlier bretylium use may give better results.