Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) can mimic multiple sclerosis (MS), leading to diagnostic confusion. We report a family with CADASIL in which the index case and the daughter of the index case were initially erroneously diagnosed with MS. Relatively specific magnetic resonance imaging (MPI) markers of CADASIL include involvement of the anterior temporal lobes and external capsules and, as illustrated in this report, these MRI findings may aid in the differentiation of the two conditions.