Aim: Acne vulgaris (AV) is a chronic, multifactorial, inflammatory disease of the pilosebaceous unit. In this study, we compare the dynamic thiol/disulfide homeostasis (TDH) of patients with AV with that of control subjects. Material and Method: In this study, the dynamic TDH in patients with AV was measured and compared with that of the control subjects using the method following Erel and Neselioglu. Results: The patient group comprised 38 female and 36 male patients, and the control group comprised 29 female and 31 male subjects. The total thiol levels were significantly lower in patients with AV than in the control subjects (p=0.044), and the disulfide/total thiol ratio was significantly lower in patients with AV (p=0.034). Plasma native thiol, total thiol, and disulfide levels did not differ significantly between the subgroups (p>0.05), and the disulfide/native thiol ratio, disulfide/total thiol ratio, and native thiol/total thiol ratio did not differ significantly among the patients with mild, moderate, and severe disease (p>0.05). Discussion: To our knowledge, this is the first study to evaluate TDH in patients with AV. Plasma thiol levels, an important component of the antioxidant system, are found to be significantly lower in AV.