One hundred consecutive patients with acute upper gastrointestinal bleeding were investigated. Blood coagulation and fibrinolytic activity were monitored by levels of plasma thrombin-antithrombin III(TAT) complex and plasmin-α2-antiplasmin (PAP) complex in samples obtained from patients at admission with haematemesis and/or melaena and in samples obtained from patients the first day after admission. Blood was transfused according to a restrictive policy. Median plasma TAT complex was significantly elevated both at admission and on the first day after admission compared with a reference group. Plasma PAP complex levels were normal at admission but decreased on the first day after admission. This decrease was independent of blood transfusion. The results indicate hypercoagulability at admission among patients with upper gastrointestinal haemorrhage reinforced by the development of a hypofibrinolytic state during the first day after admission. Restricted blood transfusion was not associated with any detectable change in blood coagulation or fibrinolysis in these patients.