To investigate the predictive value of intracranial blood flow velocity on in-hospital mortality in patients with traumatic brain injury (TBI), transcranial Doppler ultrasonography was performed in patients with mild (n=30), moderate (n=35), and severe (n=33) TBI. Bilateral middle cerebral artery was examined by transcranial Doppler ultrasonography and the time-averaged mean (Vm) velocities were used for analysis. Accelerated flow velocity (>65 cm/s) was detected in 57 (58.3%) patients. The proportion of patients with accelerated flow velocity in the moderate (62.9%) or severe TBI (69.7%) group was higher than in the mild TBI group (40%, P<0.01). Decelerated flow velocity (<35 cm/s) was detected in 11 (16.1%) patients. Five patients died during hospitalization. After adjusting age, the Glasgow Coma Scale score, and treatment measures (surgical or nonsurgical), a low flow velocity (<30 cm/s) was an independent predictor for in-hospital mortality (adjusted risk ratio, 3.6; 95% confidence interval, 1.32-11.62; P=0.01). We conclude that decelerated intracranial flow can be found in <20% of the patients with severe TBI, and a persistent flow velocity <30 cm/s is indicative of a poor clinical outcome such as in-hospital mortality.