The pathophysiology of malignant intracranial hypertension is a deleterious cycle of increased intracranial pressure, decreased tissue perfusion, declining intracellular energy production, increasing cellular edema, and subsequent increasing intracranial pressure. The use of decompressive craniectomy as a treatment to interdict this cycle, thereby improving outcome, remains controversial. Decompressive craniectomy offers an effective treatment for intracranial hypertension that is refractory to standard medical treatment. In traumatic brain injury, 2 randomized-controlled trials are underway to compare decompressive craniectomy to maximal medical management. In malignant infarction, recent randomized-controlled trials have demonstrated improved clinical outcomes in patients who underwent a decompressive craniectomy, but information on the optimal time-point remains under investigation. Definitive answers as to who will benefit, when to operate, and how the procedure is best carried out, remain as yet to be determined.