The authors report two cases of infant encephalopathies with psychomotor retardation. The cerebrospinal fluid, the electroretinogram, the electromyogram and the motor conduction velocity are normal. The neuromuscular cutaneous conjunctival biopsies are normal. No biochemical abnormalities are found. The electroencephalogram presents continuous high voltage fast rhythms (250-400 microV) with reduced or absent evoked responses. Early infantile neuroaxonal dystrophy and lissencephaly are suggested.