Hedeoma drummondii (poleo) has been used by Mexicans to prepare a tea for its pleasant taste. The methanolic extract, polar fractions, and major antioxidant compounds of the Mexican herbal tea obtained from aerial parts of H. drummondii ("poleo") showed antiproliferative effects against the cancer cell lines MCF-7 (human breast) and HeLa (human cervix). Phenolic acids isolated from poleo have significant antiproliferative effects with caffeic acid the most potent. This evidence suggests that herbal poleo tea may have chemopreventive properties.