Case 1.(EE) Female Clinical history: The earlier history and investigations have been described in detail elsewhere (2, 4, 9); intensive studies failed to reveal any haemostatic abnormality other than absence of clottable fibrinogen in the plasma. In summary, the patient was born in 1932, of parents who were first cousins, and died in 1963. She suffered repeatedly from prolonged post-traumatic bleeding, follow ing cuts, contusions or dental extractions; but bleeding could always be controlled by infusion of fibrinogen. Occasional hacmarthroses appear always to have been traumatic, and until her last illness there was no evidence of spontaneous bleeding other than superficial bruises. In 1954 the spleen was removed following traumatic rupture. This event probably was of great significane in playing a part in her final illness. Menstruation started at 15 years, and despite fears of uncontrollable loss proved entirely normal up to the time of her marriage at the age of 26 years. Thereafter, there were episodes of menorrhagia which led to recurrent iron deficiency anaemia, and an endometrial curettage was performed in May, 1962, under fibrinogen cover. In November she was readmitted with a haemoglobin of 37%(5.4 g%) on account of further menorrhagia and total hysterectomy was performed on November 15th 1962, covered by fibrinogen infusions, and without undue bleeding until 20th November (see below). Further haemorrhage form the vaginal vault occured on De cember 4th and 18th requiring packing, but for the next two months she remained well. In early'March 1963 admission became necessary for severe left sciatic pain pre sent for five weeks. There appeared to be no precipitating factor and the pain was constant. Four days after admission she had a sudden severe pain in the right buttock which was found to be due to a large haematoma. This occured spontaneously while the patient was lying in bed. The bleeding was considerable, the haemoglobin dropping from 67%(9.8 g%) to 46%(6.7 g%). As a result of numerous intravenous infusions over the years, the superficial veins had become so disorganised that intravenous in