Fetal supraventricular tachycardia may cause intrauterine heart failure and thus require transplacental treatment. During a period of nine years, we treated nine of eleven fetuses (gestational age ranging from the 26th to the 36th week) suffering from paroxysmal supraventricular tachycardia (10) or atrial flutter (1). The remaining two fetuses did not receive antiarrhythmic therapy because of only short lasting supraventricular tachycardia. Two fetuses were hydropic at the onset of therapy. Diagnosis of the rhythm disorder was established by m-mode echocardiography. All nine fetuses treated received digoxin after diagnosis of supraventricular tachycardia. Three of these reverted to sinus rhythm, one remained in supraventricular tachycardia which, however, was well tolerated. Five fetuses (three because of failure of digoxin alone and two because of a severely symptomatic supraventricular tachycardia) were treated with a combination of digoxin and verapamil. All five fetuses responded to the combined treatment, two of them, however, were delivered prematurely because of recurrence of supraventricular tachycardia in one and amnion-infection syndrome in the other. All patients survived and no severe fetal or maternal side effects were observed. Our experience confirms that digoxin and verapamil are usually effective in treating fetal supraventricular tachycardia. Some fetuses with short lasting and self limiting supraventricular tachycardia may not need any treatment, and a few not responding to digoxin and verapamil may require other antiarrhythmic drugs.