Leucodystrophies of orthochromatic type are a heterogeneous group that occur mainly in childhood and have no known enzyme deficiency. We report here the clinicopathological features of a new family of orthochromatic leucodystrophy with three main characteristics: a probably autosomal dominant inheritance; two phenotypes based on age of onset; and very few abnormalities of white matter on MRI findings in one case. The first patient, aged 58 years, had frontal dementia and epilepsy; the second, aged 38 years, had motor signs and dementia, but no epilepsy. The histopathological features of our two cases were leucodystrophy of orthochromatic subtype. However, the radiological features ( MRI and mostly FLAIR sequences) of the first case did not suggest leucodystrophy.