BACKGROUND: One-quarter of people living with human immunodeficiency virus (HIV) in the UK are unaware of their infection, leading to late presentation with consequent increased morbidity and mortality, as well as ongoing transmission of infection. Recent UK guidelines advise HIV testing of patients with 'indicator diseases' in secondary care. There are limited seroprevalence data to support this recommendation, and acute medical settings present operational difficulties that may limit its feasibility. METHODS: We conducted an audit of HIV testing rates over a 3-month period in an inner London acute admissions unit. RESULTS: Lower respiratory tract infection and fever were the most frequent indicator diseases. A total of 14% were known to be HIV positive on admission, indicating a high prevalence of HIV infection among patients presenting with indicator diseases. Of the remaining 56 patients, 29% were tested for HIV infection, with one new positive diagnosis. CONCLUSION: Longer hospital admission and infectious disease consult were associated with testing. Introduction of an HIV testing protocol based on the UK recommendations had no impact on testing rates. Given the high prevalence of HIV infection in these acute hospital settings, more intensive strategies are needed to facilitate testing.