Chronic organic solvent vapor inhalation can cause permanent damage to the central nervous system. Clinical features and radiologic abnormalities are well known, but pathology has not been definitely established. This study describes the gross, microscopic and ultrastructural changes and fatty acid composition of cholesterol esters in the brain of two chronic paint sniffers as well as the electron microscopic findings from a third, all with permanent neurological impairment. The abnormalities which were the same in all cases consisted of a demyelinating process which grossly manifested itself as brain atrophy and subtle discoloration of the cerebral and cerebellar white matter. Periodic acid-Schiff-positive macrophages in the absence of foamy macrophages were the histological hallmark of this process. Electron microscopy revealed oval membrane-bound cytoplasmic bodies filled with bundles of trilaminar inclusions composed of 3 nm paired dense leaflets separated by a space 3-7 nm wide in macrophages. Biochemical analysis showed an increase of very long chain fatty acids in the white matter cholesterol esters. This study defines the morphologic substrate of solvent vapor abuse leukoencephalopathy. The novel ultrastructural observations in conjunction with biochemical findings provide a link with adrenoleukodystrophy and raise the possibility of similar mechanisms of myelin degradation in both.