The disturbed coagulation state seen in patients with uremia has been suggested to contribute to thrombotic events in kidney grafts following transplantation. Primary haemostasis, plasmatic coagulation and fibrinolysis were investigated in eight patients before and during four weeks after kidney transplantation. In spite of an improved renal function there was postoperatively still a depressed platelet aggregation and the prostacyclin concentrations in plasma were low. The plasma coagulation seemed to be activated according to short activated partial thromboplastin time, high levels of FVIII:C and prothrombin complex. The fibrinolysis was increased and the PAI-1 levels were decreased. It is concluded that the overall haemostatic balance is characterized by a high degree of activation in uremic patients and that this activation persisted four weeks after transplantation.