This study explores the brain's response to 100% oxygen inhalation in anemic subjects using BOLD MRI. Hyperoxic challenge has previously been used to identify brain regions with increased oxygen extraction fraction from inadequate perfusion. After controlling for changes in peripheral oxygen saturation, hyperoxic BOLD response was not significantly different between sickle cell disease patients, non-sickle anemic patients and healthy controls. Therefore, our results suggest that chronically anemic patients do not have increased oxygen extraction fraction from inadequate resting oxygen delivery under resting conditions.