Background Data point to the importance of oxidative stress in rosacea. Glutathione S-transferases (GSTs) have substantial roles in a wide variety of oxidative stress-related conditions. Aim To evaluate the immunohistochemical staining characteristics of GST alpha (GSTA), mu (GSTM), pi (GSTP), and theta (GSTT) in patients with rosacea. Patients/Methods The study included 23 women and 7 men with rosacea (mean +/- SD age 49 +/- 11 year) and 15 healthy control subjects (10 women, 5 men; mean +/- SD age 47.86 +/- 10.88 year). For each patient, the average disease duration, disease subtype, ocular involvement, and severity score were recorded. A 3-mm punch biopsy was taken from the facial skin of each patient and control. Expression of GST isoenzymes was analyzed immunohistochemically. Results Expressions of GSTM1, GSTP1, and GSTT1 were significantly elevated in patients with rosacea compared to those in the control group (P = .0001,P = .0002,P < .0001, respectively). In the rosacea group, GSTT1 expression was significantly stronger than GSTP1 and GSTA1 expressions (P = .019,P < .0001, respectively). There were no significant associations between expressions of GST isoenzymes and gender, age, average duration of illness, disease subtype, ocular involvement, or severity score in the patient group (allP > .05). Conclusions In rosacea, the significant increase of GSTT1, GSTP1, and GSTM1 expressions might result from activation of GST as an outcome of extreme free radical generation from triggered neutrophils or ultraviolet vulnerability. These findings support the relevance of oxidant stress in the pathogenesis of rosacea.