We reviewed and independently ranked the measurement properties of quality of life (QL) instruments currently used in anti-dementia drug trials for Alzheimer's disease. Of 36 read reports, 5 measured and 4 mentioned QL. Eight instruments, labelled QL measures, included questionnaires measuring function, self-rating instruments measuring the caregivers' impression of the impact of sickness and deterioration of memory, and observational rating scales measuring function. The most thoroughly tested QL measure was the Progressive Deterioration Scale. The instruments with the most promising measurement properties were the Progressive Deterioration Scale and the Italian Quality of Life Scale. Most instruments now used to assess QL in antidementia drug trials have not been adequately validated in patients with Alzheimer's disease. Effort should be directed both to conceptual and practical development in the assessment of QL in dementia.