An ultrastructural study of the central nervous system of four male patients with adreno-leukodystrophy has been performed. Membrane-like cytoplasmic inclusions similar to those described in adrenal cortex, testis, and peripheral nerve were present in macrophages. These changes in widely scattered organs are probably the structural representation of a generalized metabolic disorder and are consistent with our previous hypothesis of a membrane-stability defect in these organs. (Arch Neurol 31:210-213, 1974) The concurrence of adrenal atro¬ phy and leukoencephalopathy was first noted in 1923. ' Since that Fig 1.-Scattered profiles in a perivascular macrophage in brain tissue from case 2. Each profile is composed of two electron-dense leaflets enclosing an electron-lucent space (original magnification 88,000).