Trends in HIV Seroprevalence and Risk Among Gay and Bisexual Men Who Inject Drugs in San Francisco, 1988 to 2000 *Ricky N. Bluthenthal, †Alex H. Kral, †Lauren Gee, †Jennifer Lorvick, †‡Lisa Moore, †Karen Seal, and †Brian R. Edlin *Drug Policy Research Center, Health Program, and Center for HIV Identification, Prevention, and Treatment Services, RAND, and Department of Psychiatry and Drew CARES, Charles R. Drew University of Medicine and Science; †Urban Health Study, Department of Family and Community Medicine, and Institute for Health Policy Studies, University of California, San Francisco; and ‡Department of Health Education, San Francisco State University, San Francisco, California, U.S.A. Objectives: To determine trends in HIV infection and risk behaviors among street- recruited self-identified gay and bisexual male injection drug users (IDUs) in San Francisco. Methods: Trends in HIV infection and risk behaviors were calculated for gay/bisexual (n  1594 interviews) IDUs in 26 semiannual cross sections from 1988 to 2000. Results: HIV seroprevalence among gay/bisexual IDUs decreased from the range of 35% to 45% in 1988/1989 to 25% in 1996 and then began to increase, reaching 42% in 2000. In contrast, HIV prevalence among heterosexual male IDUs remained stable during the study period. For gay/bisexual IDUs, injection and sex-related HIV risk behaviors declined modestly throughout the study period. As of the last cross section (July 2000), however, over a third of respondents reported recent syringe sharing or unprotected anal sex. Conclusions: Gay/bisexual men who inject drugs continue to be at elevated risk for HIV, suggesting that interventions such as amphetamine drug treatment and sexual risk reduction programs targeted at this population are needed. Key Words: HIV—Gay—MSM—Bisexual—Substance abuse—Injection drug use. Gay/bisexual men who inject drugs are a subpopula- tion that is at elevated risk for HIV/AIDS (1,2). Among male injection drug users (IDUs), gay/bisexual individu- als have been found to have higher HIV seroprevalence and seroincidence (3–6). Among gay/bisexual men, sub- stance use has been associated with HIV risk taking and infection (7–10). Despite these multiple risks, the pro- portion of annual AIDS cases attributable to gay/bisexual IDUs has declined from 8% in 1990 to 5% in 1998 (1). Data on AIDS cases can be deceptive because they track where the HIV epidemic has been and not where it is or where it is going. Information on trends in HIV infection and risk is required to understand the progression of the epidemic among gay/bisexual IDUs. Since 1986, the Urban Health Study at the University of California, San Francisco has collected data on HIV risk behaviors and infection among street-recruited IDUs in San Francisco through semiannual cross-sectional samples (5,11). Routinely, the men enrolled in this study have included some who identified themselves as gay or bisexual. To determine trends in HIV seroprevalence and risk among gay and bisexual IDUs, we examined data from this subsample collected from 1988 through 2000. METHODS Study Procedures Participants were recruited from street settings in four San Francisco neighborhoods (Bayview/Hunter’s Point, Mission, Tenderloin, and Direct correspondence and reprint requests to Ricky N. Bluthenthal, Associate Sociologist, RAND, 1700 Main Street, P.O. Box 2138, Santa Monica, CA 90407–2138, U.S.A.; e-mail: rickyb@rand.org Manuscript received January 23, 2001; accepted July 23, 2001. JAIDS Journal of Acquired Immune Deficiency Syndromes 28:264–269 © 2001 Lippincott Williams & Wilkins, Inc., Philadelphia 264