Traumatic brain injury (TBI) is a serious health issue in the United States, killing 100,000 people a year and serving as a source of long-term disability for many more. It is the leading cause of death in patients under the age of 45 years. Successful management of TBI requires first an appreciation that a significant part of the neuronal injury incurred following trauma is secondary and is a result of disordered homeostatic mechanisms rather than the mechanical energy of the initial insult. Key skills in the care of brain-injured patients include adequately gauging the severity of injury, recognizing the primacy of sufficient blood flow and oxygen delivery to the injured brain, and being able to detect and correct when possible local and global physiological abnormalities that frequently put the injured brain at ongoing risk within the intensive care unit. This article discusses these issues, including invasive hemodynamic and intracranial monitoring, useful methods for reducing intracranial pressure, and management of complications arising from acute head injury.