Malpractice actions against pediatricians treating patients with arrhythmias have been recurrent in four general areas. Optimal medical management may not be widely recognized. Cases illustrating the following concepts are presented. Intravenous verapamil therapy in babies may cause apnea, hypotension, and bradycardia; continued episodes of atrial flutter in a child may cause sudden death; quinidine may be related to the death; children with "familial seizure disorders" may in fact have the long QT interval syndrome. The QT interval must be measured on the ECG in patients with unexplained seizures; "supraventricular tachycardia with aberration" is uncommon in children. Rapid heart rates with QRS complexes that are different from the sinus complexes are likely to be ventricular tachycardia. These situations must be recognized as potential problems and must be treated appropriately.