The objective of this study is to describe the clinical profile of the immune reconstitution syndrome due to Mycobacterium bovis Bacillus Calmette-Guérin (IRS-BCG) in children with HIV infection who receive highly active antiretroviral treatment (HAART) at Instituto Nacional de Salud del Niño de Lima (National Children's Health Institute of Lima), Peru. A case study was conducted, including 8 children with IRS-BCG, defined as the presence of regional lymphadenopathy or inflammation on the BCG vaccination site with at least one less logarithm in the viral load or immune improvement. All patients had AIDS (C3). The starting median age in HAART was 7.2 months and the event occurred 3 to 11 weeks after the treatment was started. 7 cases showed axillary adenitis. When compared with the Non IRS-BCG group, a significant association between the age at which HAART was started at one year, severe immunodepression, and increased viral load was found. It is concluded that IRS-BCG was related to a rapid clinical progression of the mother-to-child transmitted HIV/AIDS infection, severe immunosuppression and high viral load when the HAART began.