The performance of CAMCOG, the cognitive section of the CAMDEX, is compared in a non-random sample of 222 elderly people with diagnoses based on agecat and on DSM–III criteria, and with the MMSE and some short rating scales. With a cut-off point of 69/70 and agecat organic syndrome as the criterion, the sensitivity of CAMCOG was 97% and the specificity 91%. However, 21% of DSM–III diagnoses of dementia scored above this cut-off; these were mostly mild cases. The correlation between CAMCOG and MMSE scores was 0.87, and the advantage of CAMCOG may be more apparent in longitudinal studies. Multivariate analyses showed that CAMCOG scores are affected by age, sociocultural factors and hearing and visual deficits in addition to dementia, but not by depression. There was a suggestion that individual subsections are differentially affected.