Objective:To determine the effect of Kaposi's sarcoma on survival of HIV-infected patients.Methods:Retrospective cohort study to compare the survival of 241 HIV-infected homosexual patients with Kaposi's sarcoma (cases) with that of 241 HIV-infected homosexual patients without Kaposi's sarcoma (control subjects) but with a similar level of immunosuppression (measured by the absolute CD4+ lymphocyte count).Results:Cases and control subjects were similar in age, occurrence of previous opportunistic infections, and the use of antiretroviral therapy. The mean CD4+ lymphocyte counts were similar for cases and control subjects (185 × 106versus 184 × 106/l, respectively). Cases had a higher incidence of opportunistic infections (5.95 versus 3.88 infections, respectively, per 100 person-months of observation) and a greater number of infections typical of late-stage HIV infection. Cases had a shorter overall survival than did control subjects (P= 0.0025). Kaposi's sarcoma was associated with an increased risk of death (odds ratio, 1.28), even when adjusting for age, previous opportunistic infection, baseline CD4+ lymphocyte count, and antiretroviral therapy.Conclusion:Kaposi's sarcoma appears to accelerate the clinical course of HIV infection. Opportunistic infections develop earlier and more often in patients with the disease than in control subjects. Survival was significantly shorter in patients with Kaposi's sarcoma.