The ethanol extract and ethyl acetate fraction of Mangifera indica kernel seed cake inhibited the growth of Staphylococcus aureus and Pseudomonas aeruginosa. The bioactive compounds were isolated and identified by NMR, UV and mass spectrometry as methyl gallate, gallic acid and penta-O-galloylglucose. The isolated methyl gallate and penta-O-galloylglucose also showed significant antibacterial activities against Staphylococcus aureus and Pseudomonas aeruginosa.