text: Among 12 parabens with linear alkyl chains ranging in length from C1 to C12, << heptylparaben >> (C7) and pentylparaben (C5) showed the most potent [[ ERα ]] and ERβ agonistic activity in the order of 10(-7)M and 10(-8)M, respectively, and the activities decreased in a stepwise manner as the alkyl chain was shortened to C1 or lengthened to C12.