We report on a 24 + 2 weeks pregnant woman with Marfan's syndrome, who acutely developed a dissecting aortic aneurysm with aortic valve insufficiency. Emergency surgery was performed by using hypothermic extracorporeal circulation, whilst the aortic valve and ascending aorta were replaced by a synthetic graft. Foetal heart rates, continuously monitored by using Doppler ultrasound, were shown to be closely correlated with perfusion pressures. By applying perfusion pressures of 90-100 mmHg, we were able to maintain foetal heart rates of approximately 100/min. During the first postoperative day, the CTG was normal for gestational age and no contractions were noted. During the second postoperative night, the patient prematurely delivered a dead 820 g infant (Apgar score 0/0/0/0). In view of this case report, opportunities and problems associated with an application of extracorporeal circulation during pregnancy are discussed.