Abstract. Four cases of intra‐uterine ectopic supraventricular tachycardia are described. In three there were none or only minor symptoms immediately after delivery and subsequently. The fourth baby having a congenital W–P–W‐syndrome was born with severe hydrops fetalis and was asphyxiated. From these cases and from data reported in the literature it is concluded that intra‐uterine heart failure is a significant risk when the fetal heart rate persistently exceeds 230 per minute. It is suggested that digoxin administered to the mother may be beneficial to the fetus in cases of intra‐uterine ectopic tachycardia.