Melasma is a common acquired hyperpigmentation disorder that affects mostly women and individuals with darker skin types. Oxidative stress may play a role in the pathogenesis of melasma. Dynamic thiol/disulfide homeostasis is one of the most important indicators of oxidative stress. This study aimed to investigate the presence of oxidative stress in patients with melasma by evaluating thiol/disulfide homeostasis. Sixty-seven patients with melasma and 41 healthy age- and sex-matched controls were included in the study. Disease severity was evaluated using the modified melasma area and severity index (mMASI). Thiol/disulfide homeostasis parameters of the melasma and control groups were measured using a novel, fully automated spectrophotometric method. Our data indicated the presence of oxidative stress in melasma, which may be correlated with disease severity. Because research on the presence of oxidative stress in melasma is limited, further studies are needed to support these conclusions.