Background: Glasgow coma scale (GCS) is a familiar scoring system with a standard statistical association with neurological outcome, it has many limitations that minimize its ability in prediction of Traumatic brain injury (TBI) patients' outcome. Transcranial Doppler (TCD) is a noninvasive aid in this field that can improve outcome prediction. Objective: This study aims to explore the effect of combination of GCS and Pulsatility Index (PI) in the prediction of outcome of TBI patients. Patients and Method: This study was performed in Zagazig University Hospital (ZUH). 103 traumatic brain injured patients were engaged in the investigations with hospital days of 1, 2, 3, and 7 or until patient discharge. The study was performed by TCD along with GCS recordings. Prognosis was also assessed by the Glasgow outcome scale (GOS). Results: The sensitivity and negative predictive value of PI was more than GCS in TBI patients (GCS 3-15), as they were (67.5% versus 50%) and (81.1% versus 74.3%), respectively. The combination of both PI and GCS increased the sensitivity and the negative predictive value up to 70% and 83.3%, respectively. PI had higher sensitivity, positive and negative predictive values than GCS in the identification of secondary neurologic deterioration (SND) in mild and moderate TBI patients (73.3% versus 40.0%, 61.1% versus 50.0%, and 92.0% versus 83.9%, respectively), while the combined value of both PI and GCS increased both sensitivity and positive predictive value up to 76.7% and 66.7%, respectively. Conclusion: The combination of GCS and PI would improve the prediction of outcome.