Fever is common in a variety of neurological disorders. There is abundant experimental evidence suggesting that fever leads to, or exacerbates, neuronal injury in conditions such as cerebral ischemia and traumatic brain injury. However, conclusive evidence linking control of fever to improved outcomes is lacking. It has been difficult to design studies looking at the impact of fever control on outcome, in part because traditional methods of fever control are ineffective. Recently, several new devices to control temperature have become available. These devices appear to be more effective than conventional means and might allow us to design studies that definitively answer the question: "Does controlling fever improve outcome?"