The aim of the study was to provide more comprehensive data on the clinical characteristics of hospitalized AIDS patients in Cambodia. Chart review of 381 HIV-infected patients admitted to a public hospital in Phnom Penh, Cambodia between December 1999 and May 2000 was performed. The in-hospital mortality rate was 43.6%. Approximately 50% of patients had two or more concurrent illnesses. Very advanced HIV disease was common, with CD4 cell counts below 10 cells/mm(3) in 43.2%. Only 28.3% of the patients had documentation of their HIV infection prior to hospitalization. Chronic diarrhoea was the most frequent opportunistic illness (41.2%), followed by tuberculosis (26%), cryptococcal meningitis (12.6%), Pneumocystis carinii pneumonia (8.4%), and encephalitis (4.7%). Chronic diarrhoea and tuberculosis were the most important opportunistic infections observed in HIV-infected hospitalized patients in Cambodia. These findings illustrate the need for early diagnosis of HIV-infection, effective prophylaxis for opportunistic infections and improved access to antiretroviral therapy in Cambodia.