Fetal cardiac arrhythmias are being diagnosed with increased frequency through ultrasonography and electronic fetal heart rate monitoring. Although many of them are benign, some, particularly supraventricular fetal tachycardia, have been associated with a poor outcome. Fetal hydrops and other evidence of fetal cardiac failure resulting from the elevated heart rate have been reported on. Although several modes of treatment have been described, the mainstay of cardioversion in utero continues to be digoxin. This case report demonstrates the need for prompt delivery when in utero cardioversion fails.