Objectives: To study the duration of depression, recovery over time, and predictors of prognosis in an older cohort (≥55 years) in primary care. Design: Longitudinal cohort study, with three years' follow-up. Setting: 32 general practices in West Friesland, the Netherlands. Participants: 234 patients aged 55 years or more with a prevalent major depressive disorder. Main outcome measures: Depression at baseline and every six months using structured diagnostic interviews (primary care evaluation of mental disorders according to diagnoses in Diagnostic and Statistical Manual of Mental Disorders, fourth edition) and a measure of severity of symptoms (Montgomery Åsberg depression rating scale). The main outcome measures were time to recovery and the likelihood of recovery at different time points. Multivariable analyses were used to identify variables predicting prognosis. Results: The median duration of a major depressive episode was 18.0 months (95% confidence interval 12.8 to 23.1). 35% of depressed patients recovered within one year, 60% within two years, and 68% within three years. A poor outcome was associated with severity of depression at baseline, a family history of depression, and poorer physical functioning. During follow-up functional status remained limited in patients with chronic depression but not in those who had recovered. Conclusion: Depression among patients aged 55 years or more in primary care has a poor prognosis. Using readily available prognostic factors (for example, severity of the index episode, a family history of depression, and functional decline) could help direct treatment to those at highest risk of a poor prognosis.