The prevalence of cognitive impairment was assessed among a cohort of homeless men and women selected randomly from the dining rooms of the seven largest hostels offering emergency shelter in inner Sydney. They were interviewed using sections of the Composite International Diagnostic Interview 2.0. A total of 204 subjects (155 men and 49 women) were interviewed, of whom 20 (10 percent) showed evidence of cognitive impairment as assessed by the Mini Mental State Examination. Subjects with cognitive impairment were significantly older than those without impairment (mean ages of 57 and 41, respectively). Reasons for cognitive impairment among homeless individuals are complex and remain to be elucidated.