Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an inherited disease leading to strokes and vascular dementia. The average age of onset for stroke is 45 years with a range of about 30 to 70 years. We describe a Japanese CADASIL family showing S180C in the exon 4 of NOTCH3, presenting an anticipation of the onset age for stroke. MRI demonstrated a similar extent of white matter involvement in younger and older individuals, supporting the presence of anticipation. In addition, hallucinations in 71% of affected patients, and delusions in 57% were also described. Our findings in this family suggest that a specific NOTCH3 mutation was related to unique clinical features, although such correlations have seldom been encountered in CADASIL.