Background: Several lines of investigation indicate there to be potential beneficial effects of interventions that augment cerebral blood flow (CBF) to irrigate the ischemic penumbra in acute ischemic stroke. The simplest manner to do this is to place the patient in a 'lying flat' rather than upright head position. However, any potential benefits on the brain may be offset by an increased hazard of aspiration pneumonia or exacerbation of cardiac failure in vulnerable patients. Given uncertainty over the balance of potential modest benefits and risks, and variability regarding the ideal head position policy for patients with acute ischemic stroke around the world, reliable randomized evidence is required to standardize clinical practice.