A 23-year-old patient suffering from mental deterioration was referred for CT study following her first epileptic fit. The study disclosed generalized atrophy and diffuse symmetric white matter hypodensities. Similar findings were found in her 13-year-old retarded sister. The diagnosis of metachromatic leukodystrophy (MLD) was confirmed by the finding of low arylsulfatase A (ASA) levels in cultured fibroblasts in both sisters. MRI study revealed widespread high intensity signals of T2 nature in the periventricular regions indicating changes in white matter composition.