The authors report a case of pregnancy interrupted by caesarian section at 38 weeks' gestation for attacks of fetal ventricular tachycardia. The recording of a long QT interval at birth indicated a diagnosis of fetal torsades de pointe. These attacks recurred 2 hours after birth leading to cardiac arrest. The arrhythmia was immediately controlled by betablockers therapy. The diagnostic, epidemiological and physiopathological features of the long QT syndrome are reviewed. The links with maturation of the sympathetic nervous system are recalled. Finally, a diagnostic and therapeutic strategy is proposed, based on the results of fetal echocardiography.