Objective: Prohibitin (PHB) is a highly conserved protein with pleiotropic functions. In this manuscript, we evaluated the expression and localization of PHB in the endometriosis, and explored the effect of interleukin-6 (IL-6) on the regulation of PHB in the cultured eutopic endometrial stroma cells from endometriosis patients, so as to discuss the pathophysiological roles of PHB and IL-6 in endometriosis.Methods. Normal endometrial tissues were from three normal proliferate-stage endometrium of young married women, ovarian endometriosis and eutopic endometrium from three endometriosis patients. The expression of PHB was examined by immunohistochemistry and western blot analysis. Eutopic endometrial cells from other 10 patients with endometriosis were cultured, purified and identified. The collected stromal cells were treated with IL-6 at various concentration (0 to 100 ng/ml) for 0-24 h. Then PHB expression in the treated cells was examined by real-time PCR and western blot.Results: PHB was located in the cytoplasm of both epithelial glands and stroma. PHB expression in endometriotic tissue and eutopic endometrium of patients with endometriosis was lower than that in normal endometrium. PHB levels were remarkably increased by 10 ng/ml of IL-6, at both mRNA level and protein level. This effect was reversed when the dosage of IL-6 was up to 100 ng/ml. Level of PHB mRNA significantly increased (up to 7.6 folds) after 10 ng/ml IL-6 treatment at 4 h and 8 h, which returned to basal level at 12 h, while PHB protein expression significantly increased (up to 2. 75 folds) after 10 ng/ml IL-6 treatment at 8 h and sustained through 24 h.Conclusion: PHB expression decreased in eutopic and ectopic endometrium tissues from patients with endometriosis. IL-6 had dual effect on the regulation of PHB in the cultured eutopic endometrial stroma cells. This study provided us new insights into the potential roles of PHB and IL-6 in the pathogenesis of endometriosis.