The accumulation of ascorbic acid in the brain by active transport establishes a high brain-plasma gradient of the vitamin. An insult to the CNS may result in an efflux of ascorbate into the circulation with a consequent rise of plasma levels. We measured plasma ascorbic acid levels in premature neonates on days 1, 3, and 5 of life, and the infants underwent ultrasonographic examination to detect intracranial hemorrhage. Neonates with intraventricular hemorrhage sustained significantly higher plasma ascorbate levels than their controls. Infants with massive bleeding had higher levels than those with a smaller hemorrhage. These results suggest that an efflux of ascorbic acid into the circulation occurs secondary to intracranial hemorrhage.