From October 1987 to June 1988, we attempted to determine the prevalence of HIV infection among patients hospitalized with tuberculosis and the extent of immunosuppression among those tuberculosis patients infected with HIV. Of 178 consecutive patients, 18–65 years of age, who were hospitalized with newly diagnosed, previously untreated tuberculosis, 46% (82 out of 178) had clinical or serological evidence of HIV infection, 30% (54 out of 178) were HIV-seronegative, and 24% (42 out of 178) could not be assessed for the presence of HIV infection. Among the HIV-seropositive patients without an AIDS-defining diagnosis by non-tuberculous criteria, the median CD4 lymphocyte (CD4) count was 133 ± 106cells/l (range: 11–677 ± 106); among the HIV-seronegative patients, the median CD4 count was 613 ± 106cells/l (range: 238–1614 ± 106; P < 0.001). Among the HIV-seropositive patients, those with disseminated tuberculosis (median CD4 = 79 ± 106cells/l) and those with pulmonary tuberculosis who had radiographic evidence of mediastinal or hilar adenopathy (median CD4 = 45 ± 106cells/l) had the most severe CD4 depletion, whereas those with localized extrapulmonary tuberculosis (median CD4 = 242 ± 106cells/l) and those with pulmonary tuberculosis without adenopathy (median CD4 = 299 ± 106cells/l) were less severely immunosuppressed. Of the 178 patients, 6% (11 out of 178) were infected with strains ofMycobacterium tuberculosisresistant to both isoniazid and rifampin.