Given the epidemiology of human leishmaniasis and AIDS in Brazil, numerous cases of Leishmania/HIV co-infection might be expected. Relatively few Brazilian cases have been reported, however, even from regions where the overall incidences of HIV and Leishmania infection are both relatively high. Many cases of co-infection probably go undetected because of a lack of awareness among clinicians or limited access to appropriate diagnostic methods. In contrast to the situation in Europe, intravenous-drug users do not predominate among those exposed to HIV infection in Brazil. The success of the Brazilian programme for the free and universal distribution of antiretroviral drugs has decreased the prevalences of the commoner opportunistic infections among HIV-positives and increased the longevity of AIDS cases. Recent changes in the epidemiological patterns of HIV and Leishmania infections are likely to lead to a greater degree of overlap and a greater risk of co-infection and they justify increased alertness. This review of the co-infection in Brazil addresses three main topics: the current situation, in terms of the epidemiology of AIDS and Leishmania infection; the related epidemiological trends and their likely impact on the co-infection; and the co-infection cases reported in Brazil by June 2003.