Abstract: The full-length cDNAs of estrogen receptors, ERα, ERβ, ERβ1 and ERβ2, were cloned from Xingguo red carp (Cyprinus carpio var singuonensis, Cs). The amino acid sequence of Cs ERs shared the highest identity with their counterparts of three cyprinid species. The ERs highly expressed in the liver, ovary and intestines of female Cs. In male Cs, ERα and ERβ mRNAs were mainly expressed in liver, and ERβ1 and ERβ2 mainly observed in intestine and testis, respectively. The mRNA level of ERα mRNAs was significantly up-regulated in in liver of Juveniles (150 dph) exposed to different concentrations (0.01, 0.1 and 1 nmol/L) of 17α-ethinylestradiol (EE2) for 1 and 2 weeks. The hepatic ERβ mRNA expression was dramatically increased by EE2 exposure, and ERβ1 mRNA expression was suppressed by EE2 for 1 and 2 weeks. The expression of ERβ2 mRNA was suppressed in the 1-week group with the highest suppression at 0.01 nmol/L of EE2. This study showed that EE2 differently regulated the expression of four ERs genes in liver. Compared to ERβ, ERβ1 and ERβ2, ERα is a more sensitive biomarker for short-term (1-2 week) EE2 exposure.