Introduction <p>The study of medicinal plants and their potential toxicity arises from the need to address health issues and provide immediate therapeutic solutions. The vast diversity of plants worldwide can lead to confusion regarding their use for food or medicinal purposes, sometimes resulting in intoxications that threaten human health. </p> Objective <p>To assess the acute toxicity of the ethanol extract of Minquartia guianensis Aubl ("huacapú") leaves in <i>Rattus norvegicus</i> Var. "Holtzman".</p> Methods <p>M. guianensis leaves were collected, dried, ground, and macerated to obtain the ethanol extract. Phytochemical analysis was conducted using staining and precipitation techniques. Acute toxicity was evaluated according to OECD 423 guidelines, administering a single oral dose of 2000 mg/kg to 20 rats, while 10 control rats received distilled water. Animals were monitored for 14 days, after which they were euthanized on day 15. Blood samples were analyzed for hematological parameters, and organs (brain, lung, liver, stomach, kidney, heart, spleen, ovaries, and testes) were examined for histopathological changes.</p> Results <p>No mortality was observed during the experiment. Minimal hematological alterations were detected, but these were not statistically significant. Histopathological evaluation revealed no lesions in any organs.</p> Conclusion <p>The ethanol extract of M. guianensis Aubl ("huacapú") leaves, at a dose of 2000 mg/kg, demonstrated no acute toxicity.</p>