ObjectiveTo describe a localized form ofMycobacterium avium intracellulare(MAI) infection occurring concurrently with the restoration of cutaneous delayed-type hypersensitivity (DTH) responses to mycobacterial antigens after commencement of ziclovudine therapy in immunodeficient HIV-infected patients.PatientsThe first 108 Western Australian patients with a CD4+ T-cell count of <200 $$ 106/1 and/or symptomatic disease to be given zidovudine (ZDV), of whom 72 had adequate DTH data.MethodsDTH responses to seven antigens were measured by the 'Multitest' method before and on at least two occasions during the 6 months after commencing ZDV. All patients were reviewed at regular intervals and clinical events recorded.ResultsOf the 64 patients who were anergic to tuberculin before commencing ZDV, 27 (42%) developed a DTH response to tuberculin after ZDV. Four of the nine patients with a ‘Multitest’ tuberculin response of ≥8mm and one patient who developed a positive Mantoux test toM. aviumpurified protein derivative developed an illness characterized by localized MAI infection, lymphadenopathy and/or severe fevers after 1–2 weeks.ConclusionThe development of localized MAI infection and/or fevers shortly after commencing ZDV in immunodeficient HIV-infected patients may reflect restoration of cellular immunity to mycobacterial antigens in some patients rather than early failure of therapy or hypersensitivity to ZDV.