Leishmania (Leishmania) amazonensis and Leishmania infantum (=Leishmania chagasi) are protozoa that cause American cutaneous and visceral leishmaniasis, respectively. These diseases show a high incidence in developing countries such as Brazil. The treatments used for leishmaniasis are still limited due to their high cost and toxicity. Currently, some natural products are considered an important alternative source of new leishmanicidal agents. Euterpe oleracea Martius, a palm producing black fruits, is frequently consumed in the Amazon region, as a juice, known as açai, with potent antioxidant, anti-inflammatory and anticonvulsant properties. Interestingly, the biological activity of clarified açai juice (EO) on L. (L.) amazonensis and L. infantum (=L. chagasi) is unknown. Therefore, the mechanism of anti-leishmanial action of EO has been evaluated on L. (L.) amazonensis and L. infantum (=L. chagasi). EO reduced the number of promastigotes and caused morphological alterations, increased the production of reactive oxygen species (ROS) and induced cell death phenotypes probably seems by apoptosis in the promastigotes of L. (L.) amazonensis (IC₅₀ = 1:40) and L. infantum (=L. chagasi) (IC₅₀= 1:38). EO also presented activity against Leishmania amastigotes. Treatment with EO for 72 h strongly reduced IL-17 cytokine levels at all tested concentrations and decreased the number of intracellular amastigotes in macrophages infected with L. (L.) amazonensis (IC₅₀= 1:30) and L. infantum (=L. chagasi) (IC₅₀= 1:38). Additionally, no cytotoxic effect was observed in murine macrophages treated with EO (72 h – CC₅₀ > 1:1). Our results demonstrated that EO has leishmanicidal activity against two different species that cause American visceral and cutaneous leishmaniasis without cytotoxic effects for the host cell.