The diagnosis of fetal tachyarrhythmia during a routine ultrasound scan imposes a continuous monitoring of fetal heart function through ECG and M-mode echocardiography. Since fetal dysrhythmia can lead to non-immune hydrops or to fetal death a correct diagnosis and an adequate intrauterine therapy are fundamentally important. The authors report the results obtained through a transplacental therapy with digoxin or with digoxin-verapamil in 8 cases with supraventricular tachyarrhythmia. Digoxin was very successful for conversion in sinus rhythm in 4 cases. The combination digoxin-verapamil led to the conversion in only one case resistant to the digoxin therapy.