BackgroundDepersonalisation disorder is a poorly understood and underresearched syndrome.AimsTo carry out a large and comprehensive clinical and psychopathological survey of a series of patients who made contact with a research clinic.MethodA total of 204 consecutive eligible referrals were included: 124 had a full psychiatric examination using items of the Present State Examination to define depersonalisation/derealisation and 80 had either a telephone interview (n=22) or filled out a number of self-report questionnaires. Cases assessed were diagnosed according to DSM–IV criteria.ResultsThe mean age of onset was 22.8 years; early onset was associated with greater severity There was a slight male preponderance. The disorder tended to be chronic and persistent. Seventy-one per cent met DSM–IV criteria for primary depersonalisation disorder. Depersonalisation symptom scores correlated with both anxiety and depression and a past history of these disorders was commonly reported. ‘Dissociative amnesia’ was not prominent.ConclusionsDepersonalisation disorder is a recognisable clinical entity but appears to have significant comorbidity with anxiety and depression. Research into its aetiology and treatment is warranted.