BackgroundLittle is known about self-harm occurring during the period of untreated first-episode psychosis.AimsTo establish the prevalence, nature, motivation and risk factors for self-harm occurring during the untreated phase of first-episode psychosis.MethodAs part of the æSOP (Aetiology and Ethnicity in Schizophrenia and Other Psychoses) study, episodes of self-harm were identified among all incident cases of psychosis presenting to services in south-east London and Nottingham over a 2-year period.ResultsOf the 496 participants, 56 (11.3%) had engaged in self-harm between the onset of psychotic symptoms and first presentation to services. The independent correlates of self-harm were: male gender, belonging to social class I/II, depression and a prolonged period of untreated psychosis. Increased insight was also associated with risk of self-harm.ConclusionsSelf-harm is common during the pre-treatment phase of first-episode psychosis. A unique set of fixed and malleable risk factors appear to operate in those with first-episode psychosis. Reducing treatment delay and modifying disease attitudes may be key targets for suicide prevention.