Diffusion-weighted magnetic resonance imaging (DWI) has been described as a useful tool for the diagnosis of sporadic Creutzfeldt--Jakob disease (CJD). To our knowledge, DWI abnormalities have not previously been reported in familial CJD. In two patients with familial CJD associated with distinct mutations at codon 183 and at codon 210 of the prion protein gene, DWI showed a high signal in the basal ganglia and in the cerebral cortex. These abnormalities are similar to those described in sporadic CJD. This observation expands the value of DWI for the diagnosis of some forms of familial CJD. It remains to be investigated whether this finding also holds for CJD associated with other mutations of the prion protein gene.