Objective: Supraventricular tachycardia (SVT) is the most common form of sustained fetal tachyarrhythmia in pregnancy. The development of hydrops with SVT is associated with significant worsening of prognosis. Case: We report a case of fetal SVT with hydrops at 28 weeks' gestation that required both transplacental and direct fetal treatment in a woman with concurrent obstetric cholestasis. Antiarrhythmic therapy and control of the maternal liver function and bile acid levels with ursodeoxycholic acid was associated with a fetal response to treatment resulting in a healthy term live birth. Conclusion: Fetal SVT and hydrops fetalis are associated with significant perinatal morbidity and mortality. Resistance to intensive antiarrhythmic therapies may be augmented by the myocardial effects of obstetric cholestasis and remains a challenge for management. Copyright (C) 2008 S. Karger AG, Basel.