Background: Previous studies relating smoking and alcohol drinking with the incidence of dementia have been inconsistent. Objectives: We assessed whether smoking and alcohol drinking was associated with the risk of dementia, including Alzheimer disease (AD) and vascular dementia (VaD) after seven years of follow-up. Design: We prospectively analysed the incidence of dementia from 2004 to 2011 among 2959 elderly men, according to their smoking and alcohol drinking status. Setting: six neighbourhoods from three districts mentioned in Chongqing city. Participants: A total of 3170 men were followed up annually for 7 years. Measurements: Cox proportional hazards models were established to evaluate the association between smoking, alcohol drinking and the risk of dementia. Results: The incidences of AD and VaD were higher respectively in current smoking than never smoking, daily drinking than never drinking over 7 years of follow-up (p<0.01). After adjusting for age and other potential confounders, current smoking was associated with increased risk of AD (HR= 2.14, 95% CI 1.20-4.46) and VaD (HR= 3.28, 95% CI 1.14-4.52), meanwhile, daily drinking was related to increased risk of AD (HR= 2.25, 95% CI 1.43-3.97) and VaD (HR= 3.42, 95% CI 1.18-4.51). In addition, co-smoking and drinking were related to with a significantly higher risk of AD and VaD than non-smoking and drinking (HR= 3.03, 95% CI 1.65-4.19) and VaD (HR= 3.96, 95% CI 1.64-4.71). Moreover, co-smoking and drinking had higher risk of AD and VaD compared with current smoking and daily drinking. Conclusions: Current smoking and daily drinking were found to be significantly associated with dementia in elderly men.