The potential leishmanicidal activity of interleukin‐15 (IL‐15) was examined while priming with the cytokine phorbol‐myristate‐acetate (PMA)‐activated macrophages and infecting them with Leishmania infantum parasites. The activation of macrophage cultures with IL‐15 determined a significant anti‐leishmanial activity, comparable with that induced by interferon‐gamma (IFN‐γ). The killing of Leishmania in macrophages primed with IL‐15, as well as with IFN‐γ, was followed by an increase in the IL‐12 synthesis. The neutralization of IL‐15 or IFN‐γ, by specific monoclonal antibodies (MoAb) caused a significant reduction in leishmanicidal activity. Furthermore, in PMA‐activated macrophages, the neutralization of IL‐12 production by a specific anti‐IL‐12 MoAb reduced leishmanicidal activity induced by IL‐15 and IFN‐γ. Data indicate that IL‐15 could have a role as an activator of leishmanicidal activity, directly or indirectly, by inducing IL‐12 production.