We describe the case of a pregnant woman, 35 weeks' gestation, with primary pulmonary hypertension and coarctation of the aorta requiring emergency Caesarean section under general anaesthesia. The patient had a pulmonary artery catheter inserted before operation which revealed pulmonary artery pressures in excess of 80/40 mm Hg. These were lowered using an infusion of glyceryl trinitrate. After delivery of the baby and administration of oxytocin, pulmonary artery pressures were more difficult to control. An infusion of prostacyclin was substituted which stabilized pulmonary pressures. After operation, she was transferred to the intensive care unit where prostacyclin was administered by an "aerosolized" route. Her trachea was extubated after 48 h and she made an uneventful recovery.