Five patients illustrate various aspects of obstetrical defibrination in West Malaysia, resulting from exaggeration of changes in fibrinolytic-coagulation equilibrium that occur at delivery. Hypofibrinogenaemia and fibrinolysis may occur in association or either feature predominate. These patients are from a population in which a variety of genetic and environmental factors may interact, e.g. abnormal haemoglobins, cold agglutinins, viral and other infections, introducing additional complications.