Cardiac arrhythmias are not uncommon during pregnancy. The supraventricular tachyarrhythmias have been treated successfully with digoxin, propranolol, overdrive atrial pacing, electrocardioversion, and most recently with verapamil. Verapamil is the prototype calcium channel blockers. Its use in pregnancy has been limited though the experimental effects of verapamil on fetal heart activity and uterine contractility have been studied. Reported is a case of a digitalized hyperthyroid pregnant patient successfully treated with verapamil for supraventricular tachycardia. Continuous electronic fetal monitoring was used during the period of cardioversion. The excellent response to verapamil with its apparent absence of adverse maternal or fetal side effects would suggest that the use of verapamil in the treatment of supraventricular arrhythmias in pregnancy is safe and effective.