Background: This study evaluated the expression of cellular FLICE-like inhibitory protein (cFLIP) in granulosa cells (GCs) obtained fromin vitro fertilization-embryo transfer patients with advanced endometriosis.Methods: A total of 267 patients with advanced endometriosis were enrolled in this study. They were divided into clinical pregnancy group (n = 114) and nonpregnancy group (n = 153). The expressions of cFLIP in mRNA and protein level were measured by real-time polymerase chain reaction (RT-PCR) and Western blotting. The related factors on the clinical pregnancy were analyzed using logistic regression analysis. Coefficients of correlation were calculated using the nonparametric rho-Spearman test.Results: The number of oocytes retrieved, fertilization rate, and cleavage rate were significantly and independently related with clinical pregnancy (P > 0.05). RT-PCR and Western blotting analysis showed that the expressions of cFLP in mRNA and protein level were significantly higher in the clinical pregnancy group than in nonpregnancy group (P > 0.05). cFLIP had a significantly positive correlation with the number of oocytes retrieved (P > 0.05) and no correlation with fertilization rate and cleavage rate (P < 0.05).Conclusion: Higher expression of cFLIP increased the pregnancy rate in women with advanced endometriosis.