Abstract： Objective To investigate the relationship between the distribution of nerve fibers in multiple endometriosis lesions and pelvic pain.MethodsFrom Sept.2007 to Sept.2008, 120 endometriosis patients treated in Peking Union Hospital were enrolled in this study, which including 19 cases with stage Ⅰ , 29 cases with stage Ⅱ , 44 cases with stage Ⅲ and 28 cases with stage Ⅳ.The pain symptom was evaluated by visual analogue scales(VAS) score and nerve fibers in multiple endometriosis lesions were detected by immunohistochemical staining.Results The number of nerve fibers in multiple endometriosis lesions were (29.74 ± 17.33)/mm~2 in uterosacral ligament, (24.53 ± 13.34)/mm~2 in vaginal septum, (17.09 ± 10.09)/mm~2 in uterus rectum crux, (6.77 ± 4.21)/mm~2 in peritoneal endometriosis lesions, (0.07 ± 0.25)/mm~2 in endometriosis ovarian cyst wall.The number of nerve fibers in uterosacral ligament was mostly correlated with the degree of pain (r = 0.56).The nerve fibers of uterus rectum crux and vaginalseptum were correlated with defecation pain (r = 0.58 and 0.41) and dyspareunia (r = 0.82 and 0.67),which were significantly higher than those in endometriosis leision in peritoneum and ovary.There was no significant different number of nerve fibers among different stage disease (P > 0.05).Conclusion There was significantly different distribution of nerve fibers in multiple endometriosis lesions, which was correlated with dysmenorrhea, anus pain, dyspareunia and chronic pelvic pain, not with clinical staging.