The brain requires a constant supply of docosahexaenoic acid (DHA) from blood to maintain DHA levels within the brain. Several plasma pools have been proposed to supply the brain with DHA, including plasma lipoproteins, lysophosphatidylcholine and unesterified fatty acids. Here we briefly review the evidence for each plasma pool supplying the brain highlighting controversies and remaining questions. We conclude that circulating lysophosphatidylcholine has a higher brain/body partition coefficient than unesterified DHA while unesterified DHA entry into the brain is more rapid.