Male and female siblings demonstrated similar facial features and had seizures from birth. Neurologic development, which was delayed, began to deteriorate at 1 year. Sudden death occurred at 2 8/12 and 2 3/12 years of age associated with respiratory infections. Tanning of the skin was noted 2 months before death in the first child. In the second child, blood cortisol levels failed to increase after intravenous ACTH administration, and computerized axial tomography (CAT) scans were normal. At autopsy both patients demonstrated adrenal atrophy and degenerative changes of the white matter throughout the neuraxis. We propose that these siblings have a new form of adrenoleukodystrophy that can be distinguished from the X-linked form by onset at birth, clinical appearance, and pattern of inheritance. A comparison of these cases with a second disorder, Zellweger's syndrome, suggests that a distinctive phenotype is associated with intrauterine degeneration of white matter.