GPcog is a screening tool for dementia in the aged. It consists of nine cognitive items and six items assessing the daily living instrumental activities by an informal carer. This study was aimed to assess the reliability of the French version of the GPcog in a psychogeriatric population. Two hundred and eighty inpatients from a short-term psychogeriatric ward, with or without dementia, were examined. Scores on GPcog, MMSE and on a five-word memory test for screening dementia were compared to the final diagnosis of dementia.