BackgroundThere is a bi-directional relationship between depression and chronic medical disorders.AimsThe objectives of our study were to measure the prevalence of depression in the elderly with chronic medical illness in primary care and to determine the socio-demographic and clinical factors related to depression.MethodsWe conducted a descriptive and analytical cross-sectional study of patients aged over 65, followed at the outpatient chronic diseases in Oudhref's district hospital (south of Tunisia) during the month of September 2014. We used two instruments: the activity of daily living (ADL) to determine the degree of autonomy and the geriatric depression scale (GDS) validated in Tunisia.ResultsAt the end of our investigation, 100 chronic disease patients met inclusion criteria. The average age of our population was 75 years. Prevalence of depression was 48%. The most frequent chronic pathology was hypertension (79%), followed by diabetes (70%). In analytical study, we noted no correlation between depression and socio-demographic variables such as age, sex and marital status. Regarding clinical variables, depression was significantly more frequent in patients with sensory impairments (82% vs 18%, P = 0.017), dependent (80% vs 20%, P = 0.002). Regarding chronic disease, depression was significantly more frequent in patients with respiratory disease (80% vs 20%, P = 0.033), a higher number of comorbidities (P = 0.005), who were hospitalised at least once (P = 0.015).ConclusionDepression is common in elderly with a chronic disease. Using screening instruments for major depression by primary care clinicians will help to detect depression.Disclosure of interestThe authors have not supplied their declaration of competing interest.