Alzheimer's disease associated with cerebrovascular disease is now considered as the most frequent type of dementia. The aim is to study psychopathological features and clinical evolution of mixed cases of dementia with alzheimer's and vascular brain affection. 94 patients with mixed dementia were admitted to day-clinic of Moscow Alzheimer's disease center in 2005-2006. Two control groups made up 38 patients with vascular dementia and 40 patients with Alzheimer's disease without vascular risk factors. MRI, neuropsychological examination, EEG-mapping, ultrasonography of intracranial vessels and APO E genotyping are used. The cases of mild and moderate dementia are included. Mixed dementia is four times more frequent in females since m/f ratio in VaD and AD is 1:2. Mean age for the moment of the first examination is 74,9 years for mixed cases, 71,4 years is for patients with VaD and 70,1 years for patients with AD. Mixed dementia had more frequent late onset than VaD and AD. Mild dementia is more common in patients with VaD. Non-cognitive neuropsychiatric disorders are presented in 64,8% of mixed dementia, in 57,5% of AD and in 73,6% of VaD. Transient ischemic brain attacks were in history of 71,1% VaD cases and in 13,8% of mixed dementia since were absent in AD cases. MRI picture is very different in three groups of patients. Ventricular and subarachnoidal space enlargement was common, but signs of leukoaraiosis as well as number and localization of vascular focal changes are very various. A longitudinal (5-years follow-up) prospective study is proposed.