Most questionnaires designed to assess cognitive impairment among elderly people are constructed in the West, where literacy is high. However, such questionnaires may not be applicable in developing countries because of cultural differences or low literacy. The Elderly Cognitive Assessment Questionnaire (ECAQ) is derived from items in the Mini-Mental State Examination and Geriatric Mental State Schedule. It is a satisfactory scale for quantitative assessment of cognitive impairment among elderly people living in developing countries. This 10-item questionnaire shows a sensitivity of 85.3%, specificity 91.5%, positive predictive value 82.8% and overall miscalculation rate 10.5%. In a sample of 105 elderly subjects from 2 day centres and a psychiatric outpatient clinic in Singapore, the ECAQ was compared with Kahn's Mental Status Questionnaire. The sensitivity of the scales was found to be similar but the ECAQ had a higher specificity and positive predictive value, and lower overall miscalculation rate.