Biochemical markers of cellular stress/injury have been proposed to indicate outcome after head injury. The aim of the present study was to determine whether plasma von Willebrand factor (VWF) levels correlate with primary outcome and with clinical variables in severe traumatic brain injury (TBI). Forty-four male patients, victims of severe TBI, were analyzed. Clinical outcome variables of severe TBI comprised survival and neurological assessment using the Glasgow Outcome Scale (GOS) at intensive care unit (ICU) discharge. Computerized tomography (CT) scans were analyzed according to Marshall CT classification. Three consecutive venous blood samples were taken: first sample (11.4 +/- 5.2 h after trauma, mean +/- SD), and 24 h and 7 days later. The result of mean plasma VWF concentration was significantly higher in the TBI group (273 U/dL) than in the control group (107 U/dL; p < 0.001). Severe TBI was associated with a 50% mortality rate. Nonsurvivors presented significantly higher APACHE II scores than survivors (nonsurvivors mean, 18.8; survivors mean, 12.7; p < 0.001), and also presented higher scores in Marshall CT classification (nonsurvivors mean, 4.6; survivors mean, 2.7; p < 0.05). There was a significant positive correlation between plasma levels at second plasma sampling and scores in Marshall CT classification (p < 0.05). The sensitivity of plasma VWF concentration in predicting mortality according to the cut-off of 234 U/dL was 64%, with a specificity of 68%. Therefore, VWF increases following severe TBI may be a marker of unfavorable outcome.