The proportion of elderly people in big cities of developing countries, including Vietnam, is rapidly increasing during the age of rampant urbanization. This is being followed by a sustained rise of illnesses, especially mental health issues. The objective of this study was to analyze the association between depression and the factors associated with depression among the elderly. In a cross-sectional study, 299 elderly living in Hanoi, Vietnam, were approached for data collection. Self-reported depression among the elderly was 66.9% (32.8% mild, 30.4% moderate, and 3.7% severe cases). In multivariate analysis, there were significant associations between age, number of physical activities, number of medicine intake, and 3 domains of quality of life (physical health, psychological health, and environmental health) and depression. Age and the number of medicine intake are positively correlated with depression, accounting for 57.94% and 58.93%, respectively. On the contrary, the number of physical activities and the 3 domains of quality life mentioned above are negatively correlated with depression. In the urban setting of a developing country like Vietnam, the elderly have experienced common depression. Recognizing depression among the elderly-which is individual and social-helps us design public health programs. Screening for early depression, joining social programming, and participating in physical activities may improve the mental life of the elderly.