Background: Acute disseminated encephalomyelitis (ADEM) is a rare demyelinating disease of the central nervous system that most commonly afflicts children and young adults and may be rarely seen in renal transplant patients. Most cases resolve with medical management; however, in some instances, the initial episode may evolve into a fulminant illness with malignant cerebral edema and elevated intracranial pressure that can result in a herniation syndrome with possible fatal consequences. Immediate relief of intracranial pressure is a priority and medical therapies alone may not suffice or may be precluded by compromised renal function. Case description: A case is presented of fulminant ADEM in a pediatric renal transplant patient associated with intracranial hypertension and an acute herniation syndrome with rapid neurological decline that was effectively treated with a decompressive craniectomy. The procedure was life-saving and resulted in a favorable outcome without inflicting any additional morbidity. Conclusion: Decompressive craniectomy is an effective way to rapidly reduce intracranial pressure in patients with malignant cerebral edema associated with fulminant ADEM and rapid neurological decline.