A very early case of D.S.H. (Hereditary Spongy Degeneration of the central nervous system) is described: clinical examination, C.A.T.-Scan (computerized axial tomography), biopsy and autopsy. The case presented in a 3 weeks old girl as a "colic of early infancy". During the fourth week, sudden worsening took place with attacks of dyspnea, cyanosis and frothy sputum. Ultrasound showed an echogenic thalamus. Examination by C.A.T.-Scan showed pale areas in the mid-brain and the central nuclei on both sides suggesting cerebral lesions of circulatory origin. Despite a normal lumbar puncture, cerebral biopsy was performed to exclude a potentially treatable viral condition (herpetic encephalitis?). Death took place 24 hours later. No inflammatory or spongy degenerative changes compatible with D.S.H. were found at biopsy. At autopsy however, despite superimposed recent ischemic lesions, microscopy and electron microscopy were characteristic of Hereditary Spongy Degeneration of the C.N.S. Six previous cases of D.S.H. are reported in the literature (explored by C.A.T.-Scan and confirmed histologically), this being the first report of hypodensities in the brain stem and central nuclei. In conclusion, this case shows once more that C.A.T.-Scan can be a useful tool in this still little known condition.