Hospitalized patients with HIV infection are among the most likely to benefit from the expanding availability of anti-retroviral therapy in sub-Saharan Africa. Between 1990 and 2000, 3667 people known to be HIV-infected were admitted to Kilimanjaro Christian Medical Centre (KCMC) in Moshi, northen Tanzania. The level of inpatient mortality among these patients varied from 15%-21%, and the proportion of the HIV-infected patients admitted who were female increased significantly, from 45% at the start of the study period to 52% at the end (P <0.001). When the medical records for 1683 of the HIV-infected patients who had been admitted between 1996 and 2001 were reviewed, the most prevalent diagnoses on admission were found to be pulmonary tuberculosis (21%), malaria (14%) and gastro-enteritis/diarrhoea (12%) among the adults, and non-tubercular pulmonary infection (21%), pulmonary tuberculosis (19%) and gastro-enteritis/diarrhoea (12%) among the children. The crude odds ratios (OR) for inpatient death were greatest for adults presenting with meningitis [OR=3.7; 95% confidence interval (CI)=2.1-6.7], septicaemia (OR=2.9; CI=1.2-7.3) or renal disease (OR=2.6; CI=1.2-5.7), and mortality was higher for men than for women (OR=1.4; CI=1.1-1.8). A single-day, point-prevalence survey in September 2001, among the KCMC's inpatients, identified HIV infection in 21% of those surveyed, many (44%) of the patients found positive being previously unaware of their infection. HIV infection remains a major cause of hospitalization and mortality in Moshi. A policy of routine testing would increase the number of HIV infections detected, allowing improvements in case management and in the prevention of infection.