Introduction: Supraventricular tachycardia is the most common fetal tachyarrhythmia and if persistent often associated with fetal hydrops which can cause intrauterine and neonatal death. Case Presentation: We present a case of early second trimester supraventricular tachycardia in a hydropic fetus, initially refractory to transplacental treatment. Conclusion: The supraventricular tachycardia was successfully treated when supplemented with intraperitoneal flecainide in the fetus.