Mauritia flexuosa L.f. (Arecaceae), commonly known as the buriti palm, is used in traditional medicine in Brazil. Oil from fruits is used for wound healing of skin burns and as an anti rheumatic agent. The stem pith is used to treat dysentery and diarrhea. The aim of this study was to evaluate the in vitro antibacterial and cytotoxic activities of M. flexuosa L.f. extracts and fractions. Crude ethanol extracts (EtOH) from fruits, leaves, and stems were submitted to liquid-liquid partition to yield four different soluble fractions: hexane (Hex), dichloromethane (DCM), ethyl acetate (EtOAc) and aqueous (Aq). The antibacterial activity was evaluated using the broth micro dilution method against methicillin-susceptible S. aureus (MSSA - ATCC 29213) and methicillin-resistant S. aureus (MRSA – clinical sample 155). Cytotoxicity activity was determined against five human tumor cell lines (HL-60, Jurkat, THP-1, MCF-7, and HCT-116) and Vero cell as a model for toxicity control, using MTT colorimetric assay. Across all extracts and fractions assayed, only DCM fractions from leaves and stems were active against S. aureus (MSSA and MRSA) at concentrations ranging from 31.3 to 62.5 µg/ml, and against tumor cell lines with IC50 values ranging from 20.3 to 79.0 µg/ml. The DCM fraction from stems was purified by gel permeation chromatography (GPC) to yield G1 to G12 groups. Groups G7 to G12 showed antimicrobial activity against MSSA and MRSA with MIC values of 31.3 to 125.0 µg/ml and four groups (G3, G9, G10, G12) exhibited cytotoxic activities in the range of 20 µg/ml against at least one tumor cell line. Using the hyphenated methodology, liquid chromatography-mass spectrometry (LC-MS), it was possible to identify several phenolic compounds in subgroups G7 to G10 that can be associated with the medicinal properties of stems from buriti.