Background: Whilst there is a growing body of research exploring the effect of delirium in intensive care unit (ICU) patients, the relationship between patient delirium and long-term cognitive impairment has not been investigated in settings where low rates of delirium have been reported. Objectives: To assess the associationbetweenthe incidence of delirium, durationofmechanical ventilation and long term cognitive impairment in general ICU patients. Methods: Prospective cohort study conducted in a tertiary level ICU in Queensland, Australia. Adult medical and surgical ICU patients receiving ≥12 h mechanical ventilation were assessed for delirium on at least one day. Cognitive impairment was assessed at three and/or six-months using the: Repeatable Battery for the Assessment of Neuropsychological Status (RBANS); Trail Making Test (TMT) Part A and B; and Mini-Mental State Examination (MMSE). Results: Of 148 enrollees, 91 (61%) completed assessment atthree and/or sixmonths.Incidence of delirium was 19%, with 41% cognitively impaired at three months and 24% remaining impaired at six months. Delirium was associated with impaired cognition at six-months: mean TMT Part A scores (information processing speed) were 7.86 s longer than those with no delirium (p = 0.03), and mean TMT Part B scores (executive functioning) 24.0 s longer (p = 0.04). Conclusions: ICU delirium was positively associated with impaired information processing speed and executive functioning at six-months post-discharge for this cohort. Testing for cognitive impairment with RBANS and TMT should be considered due to its greater sensitivity in comparison to the MMSE