Background. The duration of untreated psychosis has been postulated to be a predictor of clinical outcome in schizophrenia. Although several prospective studies support the relationship, some studies do not. These differences may be due to a number of methodological issues. The objectives of this study are: (i) to address many of the methodological limitations of earlier studies such as variations in sample size and selection, type of treatment provided, differences in measurement of DUP and outcome, and length of follow-up; and (ii) to examine the relationship between DUP and outcome in a prospective longitudinal study.

Method. The DUP of 200 consecutive admissions to a first-episode programme was determined. The sample was followed over 2 years and pre-morbid functioning, symptoms, social and cognitive functioning and substance use were assessed longitudinally.

Results. Two years after admission to the programme, longer DUP was significantly associated with high levels of positive symptoms and poor social functioning. Independently of other variables, DUP predicted positive symptoms and social functioning at 1 and 2 years.

Conclusions. There is evidence that long DUP continues to have an influence on outcome up to 2 years. These results support ongoing efforts for early detection and intervention.