A two year and ten-month-old girl with cerebello-brain stem leukodystrophy is presented. She was hypotonic with spasticity and showed delayed motor development until she was twelve months old, when regression of motor activities began. Progressive hypotonia, dysphagia and fatal respiratory abnormalities developed. Auditory brain stem response was absent. Pathological examination revealed primary demyelination with a predilection for the cerebellum, brain stem and spinal cord, in association with changes of the cerebellar cortex, pontine nuclei, inferior olivary nuclei and part of the basal ganglia. Clinical, pathological and biochemical studies revealed that this disease is different from metachromatic leukodystrophy, Krabbe's globoid cell leukodystrophy and adrenoleukodystrophy. The clinical entity of cerebello-brain stem orthochromatic leukodystrophy is discussed.