A growing body of evidence suggests that late-onset depression (depression occurring for the first time in later life) differs from early-onset (recurrent) depression in terms of clinical features, aetiology, neuroanatomical substrates and prognosis. Some evidence suggests that late-onset depression is more associated with somatic symptoms, cognitive deficits, cerebral structural abnormalities, vascular disease (‘vascular depression’) and poorer treatment outcomes than is early-onset depression. Both general adult and old age psychiatrists face the challenges of managing late-onset depression. In this article we attempt to clarify specific issues relating to late-onset depression in terms of clinical features, aetiology, treatment response and prognosis.