Objective:To verify the involvement of ERα and ERβ on acute and persistent pain modulation by estradiol. Methods: The involvement of both receptors on nociceptive responses was measured by tail-flick, hotplate and formalin tests in αERKO and βERKO female mice. Ovariectomies followed by estrogen replacement were performed in the groups to insure comparable sex hormone levels. Results: WT mice given E2 showed no changes in tail-flick latency and hot plate latency. There were also no significant differences between WT and αERKO or βERKO mice. Estradiol significantly reduced the overall number of flinches in PhaseⅡ(not phase Ⅰ) during the formalin nociceptive response. Using ERKO mice, we found that βERKO (not αERKO) female mice showed lower nociceptive responses compared to WT female mice in the phase Ⅱ( not phase Ⅰ) in the formalin test, but suggesting that the pain was modulated by ERβ. Conclusion: Estrogen specifically influences nociceptive responses ,and ERβ plays an important role in endogenous pain modulation systems.