A 19-year old male with severe haemophilia A (factor VIII activity less than 1%) developed terminal renal insufficiency and was subsequently dialysed via an external arteriovenous shunt for one year. To prevent bleeding he received cryoprecipitate (2000-2500 units of factor VIII) three times a week during dialysis. After one year of uneventful dialysis he received a kidney graft from a cadaver donor that was matched for the B locus antigens. During the first two weeks after transplantation his factor VIII level was kept at approximately 70% by daily cryoprecipitate infusions. Thereafter he was free from bleeding at a level of 20% with prophylactic cryoprecipitate treatment (1000 units 3 times a week). He was discharged from the hospital five weeks after transplantation with excellent renal function (ECC 75 ml/min). No rejection crisis occurred. His factor VIII requirements remained unchanged after transplantation, indicating that the human kidney does not substantially contribute to the production of clotpromoting factor VIII.