The authors assessed temporal trends in acquired immunodeficiency syndrome (AIDS) survival for 15,271 persons in San Francisco, California, diagnosed between 1987 and 1996 with an opportunistic illness included in the 1987 AIDS case definition. Predictors of survival were evaluated for 5,686 persons who were diagnosed between 1993 and 1996 and met the 1993 AIDS case definition. Median survival was 19 months for persons diagnosed between 1987 and 1989, 17 months for persons diagnosed between 1990 and 1992, 15 months for persons diagnosed between 1993 and 1994, and 31 months for persons diagnosed between 1995 and 1996. Decreased mortality was associated with use of antiretroviral therapy without protease inhibitors before AIDS (relative hazard (RH) = 0.88, 95% confidence interval (CI): 0.8, 1.0) and after AIDS (RH = 0.83, 95% CI: 0.7, 0.9) and use of antiretroviral agents with protease inhibitors before AIDS (RH = 0.25, 95% CI: 0.2, 0.3) and after AIDS (RH = 0.36, 95% CI: 0.3, 0.4). Increased mortality was found for persons aged > or = 40 years (RH = 1.43, 95% CI: 1.3, 1.6), persons initially diagnosed with an opportunistic illness (RH = 1.97, 95% CI: 1.8, 2.2), and homosexual injection drug users (RH = 1.33, 95% CI: 1.2, 1.5). Survival after AIDS has increased. Treatment with antiretroviral agents, particularly protease inhibitors, strongly predicts improved survival.