Increased intracranial pressure following traumatic brain injury is correlated with poor outcome and death in several studies. Decompressive craniectomy is a neurosurgical emergency procedure in which a large bone flap is removed and the underlying dura mater is left open in order to decrease refractory elevated intracranial pressure that is resistant to the standard measures. Currently, the results from clinical randomised trials show that decompressive craniectomy effectively lowers intracranial pressure and reduces mortality rate, but that these benefits are translated almost directly into survival with severe disability. There are, however, aspects to consider when interpreting these results and delivering the treatment to individual patients, especially in case of younger individuals. In this chapter, decompressive craniectomy and its operative technique and acute-phase complications are reviewed and discussed.