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.