Ampelozizyphus amazonicus Ducke (Rhamnaceae) is an Amazonian medicinal plant popularly known as “saracura-mira”, from which barks and roots an aqueous drink can be prepared. In an ethnopharmacological study conducted in the “quilombola” communities of Oriximina (PA), Brazil, we learnt the plant is used in the treatment of liver disorders, and as a tonic, among other uses. A trypanocidal activity for an extract of this plant has been demonstrated in literature. In this work, we investigated the effect of A. amazonicus on Trypanosoma cruzi in murine macrophages. Barks of the plant were collected and extracted twice with boiling water, filtered and dried to obtain a powder (SART). Peritoneal macrophages from BALB/c mice were infected with metacyclic forms of the Trypanosoma cruzi clone Dm 28c (3 parasites per macrophage) and some cultures were treated with A. amazonicus. Three days after infection the number of amastigotes forms was evaluated. The numbers of trypomastigote forms were determined by counting of the supernatant in a hemocytometer after 7 and 9 days of culture. In addition, we tested whether nitric oxide was involved in the mechanism of resistance to infection in our in vitro model. To address that hypothesis, peritoneal macrophages were stimulated with LPS, INF-γ and treated with A. amazonicus, and nitric oxide concentration was measured. Statistical analysis was performed using the Student t-test for independent samples, with the level of significance set at p < 0,05. Our results have shown that A. amazonicus reduces significantly the replication of amastigotes forms (35% reduction), the release of trypomastigotes forms (75% reduction) in murine macrophages infected byTrypanosoma cruzi in vitro, and that this effect does not depend on nitric oxide production. Taken together, our results suggest that A. amazonicus is a promissing natural product with important trypanocidal action in intracellular infection. Support: FAPERJ and CNPq.