Severe hypertension with arterial spasm was observed after i.v. administration of prostaglandin E2 (PGE2) during uterine exploration under general anaesthesia for control of postpartum haemorrhage. This hypertension was exceptional because PGE2 is known to cause a decrease in systemic arterial pressure. Different hypotheses for this paradoxical hypertensive crisis after PGE2 administration are discussed.