In a prospective study of adult admissions to the Department of Internal Medicine at Mama Yemo Hospital, Kinshasa, Zaire in late 1988, 129 women and 122 men were screened for HIV infection. Fifty per cent were found to be seropositive, with half of the seropositives meeting the World Health Organization (WHO) clinical AIDS definition. The HIV seropositives had a mortality rate of 50%, which was significantly higher (P = 0.004) than the 30% mortality rate seen in the seronegative group. Direct costs during hospitalization did not differ ($60.30 for HIV seropositives, $56.50 for HIV seronegatives), but pre-hospitalization expenses were significantly higher in the HIV-seropositive group ($170 for HIV seropositives, $110 for HIV seronegatives). Years of productive life lost due to death were also significantly higher for HIV seropositives versus HIV seronegatives (30.6 versus 21.3 years; P = 0.0007), and 73% of the premature mortality in the study population was attributable to HIV infection.