Objective:　To investigate the value of transcranial Doppler (TCD) ultrasonography in evaluating the outcome of severe traumatic brain injury and to correlate the TCD values with intracranial pressure (ICP) and cerebral perfusion pressure (CPP) monitoring. rn　　Methods:　A prospective study was conducted to evaluate the contribution of TCD ultrasonography to neurological outcome in a series of 96 severe traumatic brain injury patients. The quantitative variables of TCD ultrasonography included the mean blood flow velocity of the middle cerebral artery (MCA) and pulsatility index within the first 24 hours of admission. The ICP and CPP values were also recorded. Outcome in 6 months postinjury was evaluated using the Glasgow Outcome Scale (GOS 4-5 was considered as “good” and GOS 1-3 as “poor”).rn　　Results:　The mean blood flow velocity of the MCA was larger than 40 cm/s in 30 (51%) patients with good outcome whereas it was less than 40 cm/s in 27 (73%) patients with poor outcome (P<0.025). The mean PI in cases of good outcome (34 patients, 57%) was lower than 1.5 whereas in poor outcome (30 patients, 83%) was higher than 1.5 (P<0.001). The correlations of ICP and CPP to pulsatility index were statistically significant (P<0.01). rn　　Conclusions:　TCD ultrasonography is valid in predicting the patients outcome of 6 months and correlates significantly with ICP and CPP values when it is performed in the first 24 hours of severe traumatic brain injury.