The evidence, from a relatively large series of phase III trials, appears to be of moderate methodological quality, although important details are lacking and insufficient experience has been gained in trials to determine the appropriate duration of treatment. Overall, benefits are modest, subject to considerable uncertainty and are achieved at relatively high cost to the NHS, suggesting that rivastigmine is comparatively poor value for money. However, in a small proportion of people benefits are likely to be clinically significant. Treatment should therefore be targeted at those who show and sustain a response, which demands careful pre-treatment assessment and monitoring of response. Careful monitoring of adverse events is also required.