BACKGROUND: Depression is a global mental health challenge. We assessed the prevalence of depressive symptoms and their association with age, chronic conditions, and health status among middle-aged and elderly people in peri-urban Dar es Salaam, Tanzania. METHODS: Depressive symptoms were measured in 2,220 adults aged over 40 years from two wards of Dar es Salaam using the ten-item version of the Center of Epidemiologic Studies Depression Scale (CES-D-10) and a cut-off score of 10 or higher. The associations of depressive symptoms with age, 13 common chronic conditions, multimorbidity, self-rated health and any limitation in six activities of daily living were examined in univariable and multivariable logistic regressions. RESULTS: The estimated prevalence of depressive symptoms was 30.7% (95% CI 28.5-32.9). In univariable regressions, belonging to age groups 45-49 years (OR 1.35 [95% CI 1.04-1.75]) and over 70 years (OR 2.35 [95% CI 1.66-3.33]), chronic conditions, including ischemic heart disease (OR 3.43 [95% CI 2.64-4.46]), tuberculosis (OR 2.42 [95% CI 1.64-3.57]), signs of cognitive problems (OR 1.90 [95% CI 1.35-2.67]), stroke (OR 1.56 [95% CI 1.05-2.32]) and anemia (OR 1.32 [95% CI 1.01-1.71]) and limitations in activities of daily living (OR 1.35 [95% CI 1.07-1.70]) increased the odds of depressive symptoms. Reporting good or very good health was associated with lower odds of depressive symptoms (OR 0.48 [95% CI 0.35-0.66]). Ischemic heart disease and tuberculosis remained independent predictors of depressive symptoms in multivariable regressions. CONCLUSION: Depressive symptoms affected almost one in three people aged over 40 years. Their prevalence differed across age groups and was moderated by chronic conditions, health status and socioeconomic factors.