Cuphea aequipetala and Cuphea lanceolata native to Mexico are used in folk medicine. Extraction procedure standardization was performed and the amount of total phenolic compounds and flavonoids was determined in methanol extracts (obtained by stirring for 24 h) from various organs of C. aequipetala, C. aequipetala var. hispida and C. lanceolata. The antioxidant properties of extracts were compared using in vitro free radical-scavenging assays (1,1-diphenyl-2-picrylhydrazyl (DPPH^•+) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS^•+)) and the reducing power of phosphomolybdenum (PPM). A significant correlation was found between antioxidant activity and the amount of antioxidant components. Flowers of C. lanceolata showed the highest concentration of phenolic compounds (62.79±0.05 mg gallic acid equivalents (GAE)/g dry weight (DW) and the highest content of flavonoids was found in leaves of C. aequipetala (196.83±2.9 mg quercetin equivalents (QE)/g DW). The highest free radical-scavenging activity against DPPH^•+ was found in leaves of C. aequipetala var. hispida (173.33±2.12 μmol trolox/g DW), for ABTS^•+ in flowers of C. aequipetala (541.10±2.32 $\mu$mol trolox/g DW) and for PPM in leaves of C. aequipetala (1186.25±3.17 μmol trolox/g DW). Qualitative analysis indicated the presence of the flavonoid quercetin 3-β-_D-glucoside in all the species of Cuphea amongst other less polar flavonoids in C. aequipetala var. hispida. Cuphea spp. are prospective sources of phenolic compounds.