ObjectiveTo investigate the expression and function of tumor necrosis factor like apoptosis inducer(TWEAK)and fibroblast growth factor inducible 14(Fn14)in endometriosis(EMs).Methods50 EMs patients in department of obstetrics and gynecology of our hospital from June 2014 to June 2015 were selected as the subjects.Among them,30 cases were ectopic cyst wall group,20 cases were eutopic endometrium group.At the same time,20 patients who received：hysterectomy in the study group matched with the diseases of uterine fibroids and cervical lesions were collected as the control group.Gene and protein expression in different groups by immunohistochemistry,Western－Blot and RT－PCR detection of TWEAK,Fn14,according to the data analysis of TWEAK,Fn14 expression level and CA－125 level,anti endometrial antibody(EMAb),modified endometriosis stage(r－AFS)correlation analysis.ResultsThe positive rates of TWEAK and Fn14 were significantly different between the three groups,the differences were statistically significant(P＜0.05).The positive rates of TWEAK and Fn14 in ectopic cyst wall group and eutopic endometrium group were significantly higher than those in the control group,the differences were statistically significant(P ＜0.05).The positive rates of TWEAK and Fn14 in patients with EMs were significantly different in r－AFS,CA－125 and EMAb,and the differences were statistically significant(P＜0.05).According to the correlation analysis,the expression levels of TWEAK and Fn14 were positively correlated with r－AFS,CA－125 and EMAb(P＜0.05).ConclusionTWEAK/Fn14 is involved in the occurrence and development of endometriosis.Abnormal levels of TWEAK/Fn14 can lead to decreased apoptosis of endometrial cells.