In the period 1980-1985, 1641 patients were treated for tuberculosis, two of whom were known to be intravenous drug users (IVDU). One had HIV infection. Of the next 1000 patients treated for tuberculosis (January 1986-December 1989), six were HIV-negative intravenous drug users (IVDU), 18 patients were HIV-positive (12 IVDU; six homosexual/bisexual). Statistical analysis (chi 2) showed a numerically small but statistically significant (P < 0.00001, d.f. = 1, chi 2 = 20.38) increase in intravenous drug users with a diagnosis of tuberculosis. The HIV-positive patients who completed treatment responded well to anti-tuberculous drugs. The importance of tuberculosis in the context of HIV infection is that it is preventable, treatable and is the only bacterial infection to which HIV subjects are prone which can be readily transmitted to a non-HIV infected subject.