Three siblings with late infantile cerebromacular degeneration have been described. The diagnosis was confirmed in all by examination of neurons in cerebral or rectal biopsies; all showed intraneuronal lipid deposition to a varying degree. Intraneuronal lipidosis was already present at 6 months of age in the younger sibling who was clinically normal and whose electroencephalogram was normal. The 2 older siblings developed the 1st clinical signs of the disease at the age of 2 years. A critical level of intraneuronal lipidosis may be necessary, for the appearance of clinical signs and the amount of lipid stored may correlate with the clinical state of the patient.