Aims: Outcome of psychotic disorders, particularly schizophrenia and related disorders, seems to be associated, among a number of other factors, to the latency of treatment of irst episode (duration of untreated psychosis, DUP); indeed, outcome seems to be worse in subjects with a longer DUP. However, few studies addressed the topic of long term outcome and DUP as regard to cognitive functioning, though the latter plays a crucial role in explaining a significant proportion of disability both in non-affective and affective psychoses. The study aims to analyze relationships between DUP and cognitive functioning in a sample of chronic psychotic patients., Materials and Methods: We considered a unselected sample constituted by 82 chronic outpatients, 49 males (59,8%) e 33 females (40,2%), age range 20-74 yrs (mean age 46,59; s.d. 10,68 yrs); these patients were affected by schizofrenia (n=41, 50%), Bipolar Disorder type I, with psychotic mood congruent or uncongruent features (n=18, 22%,) and Schizoaffettive Disorder (n=23, 28%) according to DSMIVTR, with diagnosis confirmed by means of SCID-I. Patients underwent WAIS-R in order to evaluate cognitive functioning., Results: A longer DUP (more than 3 months between onset of first clinically evident psychotic symptoms and first antipsychotic treatment) was associated with significantly lower scores in 9 out of 11 subtests of WAIS, weighted total score, IQ-verbal score, IQ-performance score and IQ-total score. A significant relationship between a longer DUP and lower cognitive performances was confirmed among schizophrenic and schizoaffective patients, although limited to some subtests., Conclusions: The study provides new evidence for a positive association between longer DUP and worse neurocognitive functioning, even in the long term.