Cerebral pressure autoregulation (AR) is a complex intrinsic control mechanism which maintains a constant cerebral blood flow (CBF). This mechanism was found to be impaired after traumatic brain injury (TBI) and was suggested to be associated with variety of cerebrovacular abnormalities found after injury, as disturb AR might increases the vulnerability of the brain to secondary ischemic insult. Several investigators have found disturb AR response after TBI to be associated with poor outcome and increased mortality, suggesting that impaired AR might reduce the ability of injured brain to preserve an adequate blood flow in the face of hypertensive episodes. Despite the considerable diversity of methodological approaches most studies of cerebral pressure AR in patients with mild or severe TBI have show that autoregulation is often impaired, with a time course that can be quite variable. AR recovery after severe TBI can be delayed and failure to recover during the second week after injury can be found mainly in unfavorable outcome patients.