Oxidative stress is defined as a result of the loss of balance between the production of free radical or reactive oxygen species and the antioxidant system. This study aimed to determine the level of thiol-disulfide homeostasis (TDH) in the serum of women with primary dysmenorrhea. The study group consisted of 42 subjects with primary dysmenorrhea, and the control group consisted of 30 volunteer women with demographic characteristics similar to the study group. Native thiol (SH), total thiol (TSH), disulphide (SS), and SH/SS parameters were measured for TDH of the subjects. The SH (p = 0.038) and SH/TSH (p = 0.046) levels were significantly higher while SS (p = 0.013), SS/SH (p = 0.042) and SS/TSH (p = 0.046) levels were lower in the study group than in the healthy control group. The SS cut-off value was determined as 17.85 in the study group (sensitivity = 61.9%, specificity = 43.3%). Therefore, the probability of dysmenorrhea may increase significantly when SS levels fall below this value. In subjects with dysmenorrhea, there was a decrease in SS levels and an increase in SH levels in order to protect the cells and tissues from the harmful effects of free radicals.