The epidemiology of HIV and AIDS in the United Kingdom (UK) has changed markedly since highly active antiretroviral therapy (HAART) was introduced in 1996. HAART including protease inhibitors has considerably improved survival from AIDS diagnosis. The number of deaths of individuals with HIV infection in the UK, reported within 12 months of the end of the year of death, have decreased between 1995 and 1998. Concurrently AIDS diagnoses, reported within 12 months of the end of the year of diagnosis, have declined whilst diagnoses of HIV infection, similarly reported, have risen. Data from 13,689 adult AIDS cases diagnosed up to the end of 1996 were analysed. The overall median survival from AIDS diagnosis to death was 19.3 months. Over 50% of the cases diagnosed in 1996 were alive at the end of the survey therefore median survival exceeds 24 months, the maximum follow up time for the cohort. The opportunity for receiving HAART was modelled in three time periods: pre-multiple therapies (before September 1995), multiple reverse-transcriptase inhibitor therapy available (September 1995 to March 1996), and multiple therapy including protease inhibitors available (April 1996 onwards). Survival rates improved significantly among female heterosexuals and men who have sex with men when multiple therapy including protease inhibitors became available.