The antiarrhythmic effect of amiodarone was examined in this retrospective study in a group of 20 patients with a mean age of 8.5 +/- 6.7 years (range 42 days to 20 years, median 9 years). Five patients with atrial flutter, one patient with atrial fibrillation, two patients with an intermediate rhythm between atrial flutter and atrial fibrillation, four patients with chaotic atrial tachycardia, three patients with atrioventricular reentry tachycardia, two patients with junctional ectopic tachycardia, and three patients with ventricular arrhythmias were treated with amiodarone. The mean duration of therapy was 9.1 +/- 12.3 months (range 1 month to 4 years). Before amiodarone treatment, 18 patients had been unresponsive to various antiarrhythmic drugs (range 1-8, median 2). Two patients received amiodarone as an initial therapy. It was administered orally at a dose of 10 mg/kg once per day for 10 days and then decreased to 5 mg/kg once per day. Amiodarone was effective in 16 patients (80%). Side effects occurred in three patients, including thyroid dysfunction, elevation of liver enzymes, and keratopathy. All side effects disappeared upon cessation of the therapy. We recommend amiodarone for the treatment of childhood arrhythmias, especially for the refractory types.