It is questioned whether worsening of oocyte quality and oxidative stress (OS) are involved in the pathogenesis of infertility related to endometriosis and in compromised intracytoplasmic sperm injection (ICSI) outcomes. Cumulus cells (CCs) protect oocytes from entering apoptosis induced by OS. Thus, we carried out a case-control study comparing expression of superoxide dismutase 1 (SOD1), superoxide dismutase 2 (SOD2), and glutathione peroxidase 4 (GPX4; genes encoding for the main antioxidant enzymes) in CCs from mature oocytes of 26 infertile patients with minimal/mild endometriosis, 14 patients with moderate/severe endometriosis, and 41 controls undergoing controlled ovarian stimulation for ICSI, using real-time polymerase chain reaction. As a secondary objective, we investigated the interaction between the expression of these genes and clinical pregnancy (CP) by a statistical model. Only infertile women with moderate/severe endometriosis showed increased expression of the SOD1 in CCs compared to women with minimal/mild endometriosis and controls, with a positive interaction between increased expression and the occurrence of CP, suggesting that SOD1 might be a potential biomarker of CP following ICSI.