The objective of this research was to evaluate the validity of Hodkinson's Abbreviated Mental Test (AMT) in screening for dementia and to identify the optimum cut-off point to use in a prevalence survey. The study included two groups of persons: (i) a random sample of 183 individuals selected from census data, 96 of whom completed the study and (ii) another 36 persons with dementia were selected from a hospital outpatients department by sampling consecutive cases. The DSM-IV criteria were used as the "gold standard" to establish a diagnosis of dementia. The AMT was administered to the 132 participants who subsequently underwent independent clinical evaluation. In the community sample, 11 persons were diagnosed with dementia and 85 without. In the total sample, a score of 7 maximizes the efficacy of the test. The sensitivity for this cut-off point is 91.5% (78.7-97.2%) and the specificity is 82.4% (72.2-89.5%). A score of 9 gives 100% sensitivity, but the proportion of false positives rises to 66%. Our results are consistent with other studies and suggest that the AMT is a valid instrument for use in screening for dementia in populations similar to the one in this study.