We present the case of a 30-year-old parturient diagnosed in the first trimester of her first pregnancy as having paroxysmal nocturnal haemoglobinuria. Pancytopenia necessitated regular transfusion of blood products. The risks of infection, haemorrhage and thrombosis, in the presence of severe thrombocytopenia, mild neutropenia and prophylactic anticoagulation, posed management challenges. We discuss the pathophysiology of paroxysmal nocturnal haemoglobinuria and the impact of pregnancy on the disorder, particularly on maternal morbidities such as thrombosis. The issues relevant to antenatal and peripartum obstetric, haematological and anaesthetic care for vaginal delivery are considered. Severe thrombocytopenia proved a contraindication to regional techniques and she required general anaesthesia for evacuation of a retained placenta. The post-partum period was complicated by fever and a requirement for blood products. Management of these problems, of prophylactic anticoagulation and subsequent therapy, are discussed. (C) 2004 Elsevier Ltd. All rights reserved.