The objective of this chapter is to introduce the head injury. Head injury is one of the common injuries suffered by a victim of any accident. Contrary to popular belief major strides have been made over the past three decades in reducing the mortality and morbidity from head injury. The essential elements of intensive care are to maintain an optimal illness in the injured brain to facilitate healing and to prevent secondary injury to the damaged brain. Head injury can be classified in many ways such as by mechanisms, by severity, and by morphology. The diagnostic procedures available for head injury patients include CT scan, angiography, and ventriculography. Clinical presentation, diagnosis, and treatment of head injury are also discussed in this chapter.