Acquired hypofibrinogenemia is known to occur in association with a variety of clinical situations (Table 1) presenting as an abnormal bleeding tendency with or without demonstrable excessive fibrinolytic activity in the plasma. It is probably much more common than one might be led to believe from the reports in the literature. It seems unfortunate that acquired hypofibrinogenemia has not received more attention since tests for the measurement of fibrinogen levels in the blood are relatively simple and have been available for some time. The failure of a clot to form when thrombin is added to the patient's blood or plasma is suggestive of markedly depressed or absent fibrinogen levels. If normal plasma is then added and rapidly produces a clot, this is definitive evidence for hypofibrinogenemia in the patient's plasma. The clot can then be observed for lysis. Obstetrical causes of the "defibrination syndrome" are well appreciated and usually promptly