Context: Alchornea triplinervia (Spreng.) Mull. Arg. (Euphorbiaceae) is a tree widespread in many Brazilian states. This plant naturally occurs in different ecosystems including tropical Atlantic forest, Amazon rain forest, moist tropical mixed forest, savanna forest, among others. Local populations traditionally use it in tea form to treat gastric disturbances.Objective: The objective of this research was to evaluate the plant A. triplinervia as a potential inhibitor of some macrophage functions involved in the inflammatory process.Materials and methods: The effects of Alchornea triplinervia ethyl acetate fraction (AtF) on hydrogen peroxide (H2O2), nitric oxide (NO) and tumor necrosis factor-α (TNF-α) production in peritoneal macrophages were investigated using phenol red, Griess reagent and a sandwich immunoassay, respectively.Results: AtF chromatographic analyses indicate the presence of flavonoids as majority compounds. The fraction also showed an intense inhibition of H2O2 and NO production. The inhi...