Amiodarone was used in the treatment of 21 patients with supraventricular or ventricular arrhythmias which were refractory to conventional antiarrhythmic drugs, individually or in combination. Six of seven patients with supraventricular arrhythmias and 12 of 14 with ventricular tachycardia were controlled with amiodarone. Although side effects were common, only one patient was removed from treatment due to pulmonary fibrosis. We conclude that amiodarone is an effective antiarrhythmic drug for refractory ventricular and supraventricular arrhythmias.