3-Aryl-tetrahydroquinolines, aza analogues of equol, are synthesized and evaluated for their binding properties to the estrogen receptors ERalpha and ERbeta. Several of these compounds exhibited binding selectivity for ER similar to that of genistein. Compounds 8c and 8d were found to have dual actions: antagonists for ERalpha and agonists for ERbeta in a yeast two-hybrid assay. These compounds have no estrogenic effects on the uterus and bone in vivo.