In March 2018 a primigravida of 3 weeks gestation with dichorionic-diamniotic twin pregnancy presented to the emergency obstetrics department complaining of reduced fetal movements of one of the twins for the previous three days. Until admission the pregnancy had progressed without complications. One of the fetuses was diagnosed with paroxysmal supraventricular tachycardia and hydrops. Transplacental therapy with maternally administered and titred digoxin was initiated without a positive effect. Amiodarone was added to the regimen and the dose of digoxin was lowered. Combination therapy with digoxin and amiodarone was effective: sinus rhythm was restored and hydrops resolved. Both of the fetuses were delivered by an elective cesarean section in the 36th week in a good condition and with goodApgar scores. The newborn had a relapse of supraventricular tachycardia in the 3rd week of life; after hospitalization the sinus rhythm was restored and continuous antiarrhythmic therapy was initiated.