Adrenoleukodystrophy (ALD) is caused by mutations within the X-linked ABCD1 gene, resulting in the inability to transport acylated very long chain fatty acids (VLCFAs) into the peroxisome for degradation. VLCFAs subsequently accumulate in tissues, including the central nervous system. Up to 40% of boys develop a severe progressive demyelinating form of ALD, cerebral ALD, resulting in regions of demyelination observed on brain magnetic resonance imaging that are associated with a “garland ring” of gadolinium contrast enhancement. Gadolinium enhancement indicates blood-brain barrier (BBB) disruption and an active inflammatory disease process. Only hematopoietic cell transplant (HCT) has been shown to halt neurologic progression, although the mechanism of disease arrest is unknown. We evaluated imaging- and transplant-related biomarkers in 66 males who underwent HCT. In 77% of patients, gadolinium contrast resolved by 60 days post-HCT. We determined that time to neutrophil recovery and extent of donor chimerism correlated significantly with time to contrast resolution post-HCT. Graft failure was associated with a significantly slower rate of contrast resolution (P < .0001). Time to neutrophil recovery remained significant in multivariate analysis with other biomarkers (P 5 .03). Our data suggest that robust donor myeloid recovery is necessary for timely repair of the BBB.