Objectives Description of the epidemiology of mycobacterial infections in HIV/AIDS patients in Nancy. Comparison of the main features of tuberculous and non-tuberculous mycobacterial infections.Patients 58 HIV-positive patients with mycobacterial infections attended the Department of Infectious Diseases, University Hospital of Nancy from January 1985 to December 1992.Results Tuberculosis identified in 17 patients who were only moderately immunosuppressed. and had a high fatality rate (65%): no resistant strains isolated. Non-tuberculous mycobacteria (NTM) infections occurred in 41 patients who were deeply immunosuppressed and had a poor prognosis. Mycobacterium avium-intracellulare complex was the most frequently isolated species (31 cases) and showed a high level of antibiotic resistance.Conclusions NTM infections are life-threatening diseases in AIDS patients and should be systematically sought in HIV-positive patients with low CD4 + lymphocyte count.