Abstract: Objective To measure estrogenic activity when BPA and β-HCH were co-administered or administered singly using animal model without endogenous estrogens.Methods On day 17 after bilateral ovaria were excised,mice were administered with different dose of 17-E₂ developed dose-responce curve between uterine organ coefficient and POD activity.Estrogenic activity was measured after BPA and β-HCH given by intraperitoneal injection jointly or singly.Results Uterine organ coefficient and POD activity of mice were highly correlated with dose of 17-E₂.Uterine organ coefficient and POD activity significantly increased at the high dose BPA group,compared with control group(P<0.05,P<0.01).Uterine organ coefficient significantly increased at the high doseβ-HCl group,compared with control(P<0.01),but POD activity had no statistically difference.Uterine organ coefficienthad no synergistic activation in co-administered groups but POD activity elicited synergistic activation when co-administered with 100 mol/kg BW BPA+500 mol/kg BW β-HCH.Conclusion When administered with BPA and β-HCH singly,there was estrogenicity at some concentrations.When co-administered with BPA and β-HCH,they can show synergistic activation under some conditions.