PURPOSE OF REVIEW: We review immune reconstitution disease associated with mycobacterial infections in patients receiving antiretroviral treatment. We draw particular attention to data relevant to resource-limited settings and focus predominantly on publications over the past year. RECENT FINDINGS: Worldwide mycobacteria are the most important group of pathogens associated with immune reconstitution disease. In cohorts of patients with tuberculosis in high-income countries, up to one-third develop immune reconstitution disease compared with only 8-13% in current reports from resource-limited settings. We speculate on potential explanations for this difference. While most cases of tuberculosis immune reconstitution disease are self-limiting, deaths have been reported in South African and Thai cohorts. We discuss how risk and outcomes of tuberculosis immune reconstitution disease represent key variables regarding the optimum time to initiate antiretroviral treatment in tuberculosis patients. A new conceptual framework has been proposed regarding 'unmasking' of tuberculosis during antiretroviral treatment. Increasing numbers of cases of leprosy immune reconstitution disease and Bacillus Calmette-Guérin immune reconstitution disease have also been reported, mainly from resource-limited settings. Immune reconstitution disease associated with a variety of mycobacteria (tuberculous and nontuberculous) was common in a cohort of Thai children. SUMMARY: Immune reconstitution disease associated with a range of mycobacteria constitutes a challenge to delivery of antiretroviral treatment worldwide. Data concerning the pathogenesis and management of all forms of mycobacterial immune reconstitution disease are lacking.