Homeostatic mechanisms exist to enable the supply of oxygen and glucose for cerebral metabolism and neuronal function. In health, cerebral autoregulation, neurogenic and metabolic processes ensure that the supply of these nutrients is adequate to meet metabolic requirements, thus preventing neuronal cell damage. The goals of neuroanaesthesia are to provide optimal operating conditions and provide adequate cerebral blood flow, often in the context of a vulnerable brain which is exposed to the physiological stress of surgical trauma. This article outlines how delivery of anaesthesia and disease processes affecting the brain modulate the mechanisms that regulate cerebral blood flow and metabolism.