In this paper we review the cost-effectiveness of HIV counseling and testing in various settings and populations in preventing the sexual transmission of human immunodeficiency virus, and we discuss how multiple and changing goals have influenced economic evaluations of these programs. The literature indicates that these interventions are generally cost-effective if targeted to groups of infected or high-risk individuals, although there is continuing debate over the efficacy of HIV counseling and testing in changing sexual behavior. For these reasons, HIV counseling and testing programs should be part of an overall prevention strategy which also includes more intensive sexual risk-reduction interventions such as individual, small-group, and community-level approaches.