Recent studies have shown that oxidative stress increases in patients with seborrheic dermatitis; the role of the dynamic thiol/disulfide homeostasis is an important component of the oxidative stress. A new study published in the Saudi Journal of Medicine & Medical Sciences investigated the relationship between the dynamic thiol/disulfide balance in plasma of seborrheic dermatitis patients and disease severity. This was a case-control study that enrolled 70 seborrheic dermatitis patients and 61 age- and sex-matched healthy controls. Thiol/disulfide homeostasis was calculated from venous blood samples, and tests were performed by automated spectrophotometric method. The thiol/disulfide balance between the patient and control groups was compared, along with the disease severity and other demographic characteristics and thiol/disulfide balance parameters. The findings revealed that native and total thiols were significantly higher in the patient group than thatin the control group. Disulfide levels were non-significantly lower in the patient group than controls. Meanwhile, patients age and age at the onset of disease were found to have a negative correlation with native and total thiol levels. The results indicated that higher levels of thiols in the serum may be responsible for the increased proliferation of seborrheic dermatitis lesions.