To describe the pattern of survival following AIDS. National surveillance for AIDS diagnoses. AIDS cases in adults/adolescents (aged 13 years or older at AIDS diagnosis) and deaths following AIDS were notified to the national HIV surveillance centre by the diagnosing doctor through State/Territory health authorities. The date of last medical contact for each case living with AIDS was updated annually. By 30 June 1999, 4814 AIDS cases, diagnosed in Australia in 1991-1996, and 3193 deaths following AIDS had been notified to the National AIDS Registry. Median survival following AIDS was 17.7 months. Survival following AIDS increased from 16.0 months in 1991 to 27.7 months in 1996. Factors independently associated with improved survival were year of AIDS diagnosis, late HIV diagnosis, CD4+ cell count greater than 50 x 10(6) cells/l, age of less than 45 years and presentation with Pneumocystis carinii pneumonia only or Kaposi's sarcoma only. The risk of death declined over time when the initial AIDS-defining illness was Pneumocystis carinii pneumonia only [adjusted hazard ratio (AHR) = 0.91, P < 0.0005]; other opportunistic infections (AHR, 0.88; P < 0.0005); Kaposi's sarcoma only (AHR, 0.92; P = 0.025); and central nervous system conditions (HIV encephalopathy, cryptococcosis, toxoplasmosis) (AHR, 0.92; P = 0.012). No time trend was observed for survival following diagnoses of non-Hodgkin's lymphoma or other multiple illnesses. Survival following AIDS has improved in Australia, especially among cases diagnosed in 1995 and 1996. Temporal improvements in survival following AIDS were coincident with the introduction of combination antiretroviral treatment for HIV infection and suggest that treatment is effective in limiting disease progression among people with advanced HIV infection.