Between May, 1983 and September, 1987, 8 per cent of the patients hospitalised for an HIV infection (i.e. 30 patients, 20 with an ARC and 10 with AIDS) had tuberculosis. The percentage of patients originating from Central Africa or Haiti was important (23 per cent). Tuberculosis was thoracic (76 per cent) and/or extrathoracic (63 per cent). The main organs involved were the lungs (n = 21), the mediastinal lymph nodes (n = 9), the superficial lymph nodes (n = 9), and the liver (n = 8). The pulmonary infection was often multilobar (n = 14), but without caverns. The tuberculin PPD (purified protein derived) test was positive in 63 per cent of ARC patients and in 30 per cent of AIDS patients. The diagnosis of tuberculosis was confirmed in 27/30 patients by culture of Mycobacterium tuberculosis (n = 23) and/or histology (n = 13), and in the remaining patients by response to a specific treatment. In 3 patients with normal X-ray film of the chest, M. tuberculosis could be recovered by culture of the gastric fluid. Antituberculous treatment was effective, but its optimum duration is to be determined since relapse may occur, even after one year of treatment. The side-effects of the treatment were unusually frequent (54 per cent). The occurrence of tuberculosis seemed to aggravate the prognosis of the HIV disease, since 57 per cent of the ARC patients reached the stage of AIDS within 6 months on average. These results are in agreement with the new recommendations of the Centers for disease control which include extrapulmonary tuberculosis in the AIDS criteria. However, in our study, pulmonary tuberculosis had the same detrimental effect and should therefore be included in the AIDS criteria.