The authors present a case history of supra-ventricular tachycardia (SVT) diagnosed in a fetus after 32 weeks of amenorrhoea in a 2-para woman of 29 years. This SVT was discovered after an urgent consultation had been asked for when uterine contractions started after the uterus had been over-distended. The diagnosis that had been suspected when it had been impossible to measure the fetal heart rate by a monitor was confirmed when the rate was found to be 270 beats per minute using TM ultrasound. A complete detailed ultrasound examination showed that there was generalised oedema (anasarca). Searching for a congenital malformation revealed none. Other tests eliminated other causes for the anasarca. Treatment was rapidly instituted by injecting 2 and later 3 ampoules of 0.25 mg of Digoxin in 24 hours. This did not change the fetal heart rate although continued for five days. Adding Amiodarone into a transfusion at the rate of 3 ampoules in 24 hours slowed the fetal heart rate to 220 beats per minute within 24 hours. After 3 days treatment with Amiodarone the heart rate went into sinusal rhythm. A boy weighing 3,410 g was delivered by caesarean section 3 days later after the membranes had ruptured prematurely. The placenta weighed 1,750 g. The newborn infant was transferred into a special care baby unit where it progressed favourably. The child left the unit after six weeks on treatment with Digoxin. Consulting the literature has shown under what circumstances the condition can arise and the ways of diagnosing it and the differential diagnosis of fetal SVT, as well as methods of treatment.(ABSTRACT TRUNCATED AT 250 WORDS)