We evaluated the in vitro antibacterial activity of extracts and fractions of Physalis peruviana L. calyces and flowers and leaves of Caesalpinia pulcherrima (L.) Swartz against ATCC strains Staphylococcus aureus, Klebsiella pneumoniae and Pseudomonas aeruginosa, determining the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). We find potent activity with MIC ≤ 0,256 mg/mL for the chloroform fraction of P. peruviana calyces, the ethanol fraction of flowers of C. pulcherrima and ethanol and ether fractions of leaves of C. pulcherrima. Based on these results, we conclude that both species are promising and it is recommended to continue exploring them in order to isolate, purify and to elucidate the chemical structure from those compounds responsible for the biological activity of each active fraction.