PurposeTo study the characteristics of contingent negative variation (CNV) in vascular dementia.MethodsCNV was tested and compared in 24 vascular dementia (VD) patients and 22 normal aged persons. Results The data showed that in compare with normal controls the latencies of early component and late component of CNV in VD were greatly prolonged and closely correlated to the extent of dementia. The amplitude of early component was greatly reduced. The reactive time (RT) was prolonged prominently and also correlated with the extent of dementia. The occurrence of postimperative negative variation (PINV) increased. Conclusions The value of CNV can be used to reflect the extent of dementia. Test the CNV in series may help to evaluate the cognitive impairment in VD.