FEBRUARY 2009 — This publication updates projections prepared in 2000 and adds two new components, MSM and ART. Projections are based on the assumption that risk behaviors and STI rates remain unchanged from 2005 onward. The 2005–25 projections show a slow decline in number of new infections and a shift in the dominant modes of HIV transmission. They also indicate the need for the Thai government to make a long-term commitment to provide ART to a large and growing number of people. Effective prevention interventions, keeping the costs of ART low, and improved adherence are also needed. The publication was prepared by the Analysis and Advocacy (A2) project.