BACKGROUND: Our study aims to investigate whether there is a relationship by measuring the total oxidant/antioxidant load with the thiol/disulfide method in patients with unexplained infertility. METHODS: A total of 82 participants were enrolled, consisting of 41 women with unexplained infertility and 41 fertile controls matched for age and body mass index (BMI). Hormonal profiles, including follicle-stimulating hormone (FSH), luteinizing hormone (LH), estradiol (E2), thyroid-stimulating hormone (TSH), and prolactin, were assessed using the chemiluminescence immunoassay method. Thiol/disulfide homeostasis was evaluated using a validated automated spectrophotometric method, which measured native thiol (NT), total thiol (TT), and disulfide levels. Detailed quality control measures ensured the reliability of the results. RESULTS: In the study, no significant difference was found between the infertile and fertile groups' demographic (age) and clinical variables in terms of height, weight, BMI, FSH, LH, E2, TSH, prolactin, antral follicle count, TT, NT, and disulfide values (P >
.05). The rates were found to be greater in the infertile group in disulfide/NT ratio and disulfide/TT ratio compared to the fertile group, even though there was no statistically significant difference between the groups' disulfide/NT ratio, disulfide/TT ratio, and NT/TT ratio values. The fertile group, however, had a higher NT/TT ratio rate. CONCLUSION: Although the unexplained infertility and fertile groups in the study did not differ in serum thiol and disulfide levels, the infertile group was found to have a relatively high disulfide/thiol ratio. More prospective studies on thiol/disulfide balance related to unexplained infertility may help to understand the relationship.