Because it has been difficult to predict the outcome of patients with head injury in the early period after admission, a clinical study was undertaken to evaluate if the fibrinolytic parameters could be reliable indicators of outcome. Seventy patients presenting with head injury without obvious trauma in other regions were studied, and plasma levels of alpha2-plasmin inhibitor-plasmin complex (PIC) and D-dimer on admission (within 2 hours postinjury) were assessed. Plasma levels of both PIC and D-dimer were elevated and correlated well to patient outcomes. When plasma PIC levels were higher than 15 microg/ml or D-dimer levels were higher than 5 microg/ml, 92% of patients died regardless of their consciousness level on admission, whereas all patients made good recoveries when their PIC levels were less than 2 microg/ml or D-dimer levels were less than 1 microg/ml. Therefore, plasma levels of both PIC and D-dimer on admission were revealed to be reliable prognostic markers of head injury. Using these markers, patients with poor outcomes (progressive brain injury), such as "talk and deteriorate" types, could be readily identified on admission.