© 2020, Springer-Verlag GmbH Germany, part of Springer Nature.Atopic dermatitis (AD) is a chronic disease of infancy and its pathogenesis remains unclear. There are recent studies suggesting that oxidative stress could play a role in the pathophysiology of atopic dermatitis. The aim of this study was to evaluate thiol (SH)–disulfide (SS) hemostasis as a new marker of oxidative stress (OS) in infants with atopic dermatitis. Thirty-one infants with AD and 30 healthy infants were included in a prospective, cross-sectional study. PO-SCORAD Index of infants with atopic dermatitis was calculated at the time of sample collection. Total antioxidant status (TAS), total oxidant status (TOS), native thiol (–SH), total thiol (–SH + –S–S–), and disulfide (SS) were measured in the control and patient groups. SS/SH, SS/total SH, SH/total SH ratios were compared between the groups. Mean native thiol and total thiol concentrations of the patient group were lower than the control group (p = 0.012; 0.047). The mean disulfide concentration of the patient group was significantly higher than the control group (p = 0.025). SS/SH, SS/total SH, and SH/total SH ratios were significantly higher in the patient group than in the control group (p < 0.05). There was a positive correlation between the duration of the breasting of the patients and thiol concentrations (p = 0.000). In our study, we found increased oxidative stress and decreased antioxidant defense mechanisms in infants with AD. Dynamic thiol–disulfide balance in the patient group was weakened and the balance shifted towards the oxidative side. These results may shed light on etiopathogenesis of atopic dermatitis and be useful in the development of new therapeutic methods.