A new lethal familial syndrome of unknown etiology is described in two male siblings who died in the newborn period. Both had corneal edema and were hypotonic, requiring assisted ventilation at birth. Neuropathological findings included an immature appearance of neocortical neurons, with cortical architecture similar to that normally seen in an infant of 5 months gestational age. Axons and myelin were absent in the cerebral and cerebellar white matter, and also in descending white matter tracts of brainstem and spinal cord. Subacute inflammation was seen in the anterior horns of the spinal cord in both cases, although there was no evidence of inflammation elsewhere in the nervous system. Electron microscopy of endothelial cells from brain, spinal cord and a number of other tissues of the second sibling showed tubuloreticular inclusions (TRIs). There are no known previous reports of similar neuropathology. Future recognition of this condition will be important for genetic counselling.