The species Minquartia guianensis (Olacaceae) is found in the Amazon region and also in Nicarágua, Panamá and Costa Rica. Indigenous people from Ecuador use the bark infusion for intestinal infections treatment caused by parasites, against muscular pain and cutaneous irritations. For this reason, the aim of this work was to evaluate the antibacterial activity of M. guianensis extracts over Gram-negative (Shigella flexneri M90T, Salmonella choleraesuis 6958, Escherichia coli E2348/69) and Gram-positive bacteria (Methicillin-Resistant Staphylococcus aureus 33591, Methicillin-Sensible Staphylococcus aureus 25923, Bacillus cereus 9634, Bacillus liquefaciens clinical isolated). These bacteria are diarrhea related, which causes several child death in tropical regions. The active extract is under fractionation (leaf DCM) and until now, four triterpene were isolated lupeol, taraxerol, lupenona and squalene, but it was not possible yet to assay the substances, because of their small amount.