Background: The demographic aging of the Algerian population increases the risk of some age-related pathologies, including dementia. It is one of the most significant public health problems. The prevalence of dementia and risk factors has not been fully investigated in Algeria. This study aims to improve the knowledge of dementia in Algiers by determining its risk factors, allowing to enrich its epidemiology and social aspects. Methods: A cross-sectional, door-to-door study in the Department of Sidi M’Hamed in Algiers “Algeria», conducted in general population, was carried out between June 2012 and August 2014. The clinical diagnosis of dementia was made according to the Diagnostic and Statistical Manual of Mental Disorders,4th Edition (DSM-IV) criteria. Possible or probable cases of Alzheimer’s Disease (AD), Mixed Dementia (MD), Vascular Dementia (VD), Frontotemporal Dementia (FTD), Parkinson’s Dementia (PD), and other dementias were identified using standard criteria. Sociodemographic characteristics, lifestyle and the pathological history were recorded. Results: 3896 subjects aged 60 years and over participated in the study. Among them, 192 had dementia. Factors strongly associated with dementia in the department of Sidi M’Hamed were advanced age, living alone, widowhood, low cultural level, family history of dementia, high blood pressure and stroke (p<10−6). Conclusion: Greater age, low social raise, low level of education and vascular risk factors (stroke and high blood pressure) increase the risk of suffering from dementia. Other more extensive studies should be conducted, both in rural and urban areas of Algeria, in order to consider comprehensive management solutions and prevention approaches adapted to our context.