Background: Although transition rates in 'ultra-high risk' (UHR) for psychosis samples are declining,many young individuals at UHR still experience attenuated positive symptoms and impaired functioning at follow-up. The present study examined the association between a history of childhood trauma and transition to psychosis, and symptomatic and functional outcome, in UHR patients. Method: Data on childhood trauma were available for 125 UHR individuals. Cox regression and linear regression analyseswere used to determine the association between childhood trauma, and clinical and functional outcome, during the 24-month follow-up. Results: Of the 125 UHR subjects 26 individuals (20.8%) transitioned to psychosis within 24 months. Childhood trauma did not predict transition to psychosis. However, at 24-month follow-up, UHR patientswith higher levels of childhood trauma had higher levels of attenuated positive symptoms (b=0.34, t=2.925, p < 0.01), general symptoms (b=0.29, t=2.707, p < 0.01) and depression (b=0.32, t=2.929, p < 0.01) and lower levels of global functioning (b = -0.33, t = -2.853, p = 0.01). Childhood trauma was not significantly associated with a differential course of symptoms over time, although in those with higher levels of childhood trauma, attenuated positive symptoms were more persistent at a trend level. Conclusions: Our results suggest that childhood trauma may contribute to a shared vulnerability for several psychopathological domains.