This article uses longitudinal data from a primary care sample to examine long-term prognosis of depression. A sample of 225 patients initiating antidepressant treatment in primary care completed assessments of clinical outcome (Hamilton Depression Rating Scale and the mood module of the Structured Clinical Interview for DSM-IIIR) 1, 3, 6, 9, 12, 18 and 24 months after initiating treatment. The proportion of patients continuing to meet criteria for major depression fell rapidly to approximately 10% and remained at approximately that level throughout follow-up. The proportion meeting criteria for remission (Hamilton Depression score of 7 or less) rose gradually to approximately 45%. Long-term prognosis (i.e. probability of remission at 6 months and beyond) was strongly related to remission status at 3 months (odds ratio 3.65; 95% confidence interval, 2.81-4.76) and only modestly related to various clinical characteristics assessed at baseline (e.g. prior history of recurrent depression, medical comorbidity, comorbid anxiety symptoms). The findings indicate that potentially modifiable risk factors influence the long-term prognosis of depression. This suggests that more systematic and effective depression treatment programmes might have an important effect on long-term course and reduce the overall burden of chronic and recurrent depression.