Phytoestrogen has previously been proposed as an alternative to hormone replacement therapy. Hispolon has been found to have phytoestrogenic properties. However, the possible effects of hispolon on estrogen receptors and other related molecules remain to be determined. This study was performed mainly to confirm the estrogenic function of hispolon as it relates to estrogen receptors, aromatase, and cyclooxygenase 2 (COX-2). Hispolon was shown to increase the serum 17β-estradiol in vivo. Immunohistochemical staining methods showed that hispolon exhibited a biphasic effect on ERα/β and aromatase expression in MCF-7 cells. Hispolon could also significantly inhibit aromatase activity, assessed using the enzyme-linked immunosorbent assay. Western blotting showed that COX-2 and aromatase could be inhibited by hispolon. These results further prove the phytoestrogenic features of hispolon and explore some pharmacological mechanisms that suggest that hispolon could be useful in the treatment of breast cancers or other gynecologic diseases.