Objective To investigate Alzheimer's disease(AD) and vascular dementia(VD) status and distribution in middle-aged and elderly population in Xinjiang Uigur and Han nationalities to provide the data for the further study of the causes and prevention of AD. Methods From July 2004 to June 2007, according to the DSM-Ⅳ-R diagnostic criteria for dementia and N1NCDS-ADRDA criteria, multi-stage stratified random cluster samphng approaches were adopted in 6 areas in southern, eastern, northern Xinjiang Urumqi City Community to investigate middle-aged and elderly Uigur and Han people older than 50-year-old suffering from AD. Results A total of 8284 were surveyed, Xinjiang AD crude prevalence rate was 3.66%, Uigur and Han AD accounting for 3.24% and 4. 19% respectively. According to the age composition of 2000 census of Xinjiang, AD adjusted standardized incidence was 3.50%, 2. 68% and 4. 31% for Uigur and Han respectively; Xinjiang VD crude prevalence rate was 1.05%, with Uigur and Han VD crude prevalence rates being 1.11% and 0. 97% ,respectively. Xinjiang VD standard rate was 0.98%, Uigur and Han accounting for 1.00% and 0. 96% respectively. Prevalence rate of men and women had significant differences among age groups, and increased along with age (Uigurs χ2= 186. 286, P = 0. 000 ; Hans χ2=77. 131 ,P =0. 009). The Uigur, Han AD prevalence rates obviously reduced with the increase of educationallevel(Uigurs χ2=12.291,P=0.002;Hans χ2=61.539,P=0.000). Conclusions AD standardized rate in the elderly in Xinjiang Uigur and Hart ethnic groups is significantly higher than the national average. AD prevalence rate is comparably higher than that of VD. There are significant differences among the nationality, gender, age and culture.