Brain edema following ischemic stroke often results in significant morbidity and death. Decompressive craniotomy has been advocated and may result in a surprisingly satisfactory outcome. We present a 17-year-old patient who developed a right middle cerebral artery territory infarction associated with a cardiac myxoma. Five days after the ictus and two days after a thoracotomy to remove the obstructing tumor, he developed clinical signs of uncal herniation. CT scans showed massive cerebral edema and development of obstructive hydrocephalus. An intracranial pressure monitor measured 30 mmHg on insertion. Management with mannitol reversed the clinical and radiologic signs of uncal herniation. There is a renewed interest in decompressive craniotomy. Our patient indicates that conventional management of increased intracranial pressure may reverse brain edema when associated with hemispheric infarction. Decompressive craniotomy needs validation in a randomized trial.