The purpose of this study is assessing informative capability of the most frequently used scales and neuropsychological tests evaluating cognitive function for mild cognitive impairment (MCI) and vascular dementia (VD). A total of 104 patients with cerebrovascular disorder including 39 male and 65 female were divided into two subgroups depending on severity of the cognitive impairment. The first group consisted of 51 patients with MCI and the second one consisted of 53 patients with VD confirmed by MMSE and MoCA-test. The obtained correlation analysis data testifies to difficulties in the interpretation of these routinely used scales not only because of the differences between investigated parameters of the patients with MCI and VD, but also because of the main goal of their creation. Most of the scales were created for patients with dementia and now their sensitivity for MCI is doubtful. The MoCA test, Clock Drawing Test (CDT) and ADAS-cog subscale are more sensitive and has greatest informative capability for patients with MCI and dementia, while MMSE is more informative mostly for patients with dementia. Neuropsychological tests DAD and NPI remain informative in varying degrees of cognitive impairment. In the diagnosis and differential diagnosis of the degree of cognitive impairment of vascular genesis, one should use not only a complex of scales and neuropsychological tests, but also methods that comprehensively reflect the vascular genesis of the process of formation of cognitive impairment.