Background: Indigenous Australians have a unique cultural heritage dating back many thousands of years. Unfortunately, there is no validated tool to assess cognition in older indigenous Australians. This study was designed to address this deficiency. The Kimberley Indigenous Cognitive Assessment (KICA), vas developed with Indigenous health and aged care organizations, and comprises cognitive, informant and functional sections. The psychometric properties of the cognitive assessment section (KICA-Cog) are described in this paper.Methods: The KICA-Cog was tested in 70 indigenous subjects, of varying cognitive abilities and diagnoses, over 45 years of age. Subjects were interviewed using the KICA-Cog and then independently assessed by expert clinical raters using DSM-IV and ICD-10 criteria. Interrater and internal reliability were determined.Results: The KICA-Cog score showed no systematic interrater difference; the mean was -0.07 (SD = 1.83). Interrater reliability for 16 individual questions from the cognitive section revealed a kappa-value >= 0.6 and intraclass correlations for 12 questions. Internal consistency, as assessed by Cronbach's alpha, was 0.88. Three items on the cognitive score (pension week, recall and free recall) effectively discriminated 85-7% of dementia cases. Sensitivity and specificity were 90.6% and 92.6%, respectively, using a cut-off score of 31/32.Conclusions: The KICA-Cog appears to be a reliable assessment tool for cognitive impairment in an Australian older traditionally living indigenous population.