tThe “bacuri” (Platonia insignis Mart., Clusiaceae) is a native tropical fruit from the Brazilian Amazon andNortheast Regions. Its seeds are used to treat inflammatory diseases, diarrhea and skin problems intraditional medical practices. Regarding its widespread medicinal uses, it is important to evaluate thebiological and toxicological potential of this species. This way, the aim of this study was to investigatethe in vitro cytotoxic and immunomodulatory effects of the hexanic extract of P. insignis seeds, as wellas its in vivo acute oral toxicity. The biological evaluation was performed by the determination of cyto-toxic (MTT and hemolysis assay) and immunomodulatory (phagocytic capacity, lysosomal volume andnitrite production) activities of EHSB in murine peritoneal macrophages. In addition, the oral acute tox-icity was evaluated using female Wistar rats treated with EHSB (2.0 g/kg), in accordance with the OECD423 Guideline. The EHSB showed low toxicity for macrophages in the MTT test (CC50value: 90.03 g/ml),as well as for erythrocytes, which caused only 2.5% hemolysis at the highest concentration. A strongimmunomodulatory activity was observed by a markedly increase of the NO production, phagocytic abil-ity and lysosomal volume. On the other hand, it was not observed deaths or changes in the clinical andbehavioral parameters in the toxicological evaluation. This manner, the present study contributes to theknowledge about the immunomodulatory and toxicological properties of the P. insignis. This may provideperspectives for the evaluation and development of effective and safe phytomedicines created from theBrazilian local biodiversity.