Background: Dysthymia (DD) may be thought of as depression associated with personality disorder, a phase in the pleomorphic natural history of unipolar depression or a result of exposure to chronic physical illness. Prevalence, clinical features, risk factors and prognosis may change with age. Method: Large (n=3056) representative sample of elderly (55-85) in the Netherlands. Two-stage screen procedure to identify elderly with DD. The Center for Epidemiologic Studies Depression scale (CES-D) was used as a screen and the Diagnostic Interview Schedule (DIS) to diagnose DD. Data on 277 depressed elderly were available to assess the 6-year prognosis of DD. Results: The prevalence of DD (4.61%) was higher in women and declined with age. The symptom profiles of DD and MDD were very similar. Those with DD were very likely to have had MDD earlier in life (44% in pure DD and 80% in those with double depression). The average age at onset (31 years) was earlier than in MDD (53 years). Environmental and personal vulnerability dominated the risk-factors. The prognosis was unfavourable in most cases. Limitations: Considerable attrition and retrospective data on age at onset and previous histories of depression. Conclusion: Although the prevalence declines with age, DD remains common in later life. Many cases arise later than is often thought and clinical features intertwine with those of MDD in the course of life. Given the unfavourable prognosis, provision of effective treatment is warranted.