KIE: Britain's Department of Health has proposed a program of extensive human immunodeficiecy virus (HIV) testing of unlinked anonymous blood samples from patients in a variety of health care settings in England and Wales. The program's aim is to provide estimates of the prevalence of HIV infection in the population, and of the rate of change of prevalence estimates over time. This information will be used to target prevention campaigns to high-risk populations, and to determine future allocations of health funds. The disadvantages of present British methods of serosurveillance for HIV and the advantages of the unlinked anonymous method are described. Principles of the latter method of data collection and details of the proposed Department of Health program are outlined. A discussion of legal and ethical considerations in unlinked anonymous HIV testing concludes this review.