Objective:To understand the prevalence of depression in rural middle-aged and elderly people in Bayannur City, Inner Mongolia Autonomous Region, and to explore the relationship between arsenism and depression.Methods:In December 2016 and April 2018, a one-to-one interview questionnaire survey was conducted among middle-aged and elderly people aged 45 and above in rural areas of Bayannur City, and their depression and arsenism were analyzed. Multivariate logistic regression was used to analyze the relationship between arsenism and depression.Results:A total of 870 rural middle-aged and elderly people in Bayannur City were included, and the detection rate of depression was 15.3% (133/870). The detection rates of depression in arsenism and non-arsenism were 20.8% (37/178) and 13.9% (96/692), respectively, the difference was statistically significant (χ 2 = 4.67, P = 0.030). Multivariate logistic regression analysis after adjusting for factors associated with depression showed that people with arsenism were 1.8 times as likely to be depression compared to those without arsenism [adjusted odds ratio ( AOR) = 1.8, 95% confidence interval ( CI): 1.1 - 3.1, P < 0.05]. Conclusion:The detection rate of depression among rural middle-aged and elderly people in Bayannur City is relatively high, and arsenism may increase the risk of depression.