Acne vulgaris is a common, inflammatory disease of the pilosebaceous duct. Propionibacterium acnes proliferated in sebum, produces chemotactic factors followed by phagocytosis and this process results in the production of reactive oxygen species which contribute to the inflammatory reaction in papulopustular type acne. Benzoyl peroxide (BP) and BP combination with erythromycin (BP/E) are effective topical medications for the treatment of mild and moderate acne vulgaris. In the present study, the effects of BP and BP/E on antioxidant defence enzymes in 40 patients with papulopustular type acne were evaluated. The activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT), and also thiobarbituric acid reactive substance (TBARS) levels were determined in peripheral blood leukocytes in all patients, as well as in tissues of a small group of patients before and at the end of 4 weeks of treatment. No difference was detected in leukocyte antioxidant enzyme activities and TBARS levels due to BP treatment. However, SOD, CAT and GSH-Px activities in leukocytes decreased and TBARS levels increased in BP/E-treated patients (p < 0.05). There was no statistically significant difference between pretreatment and posttreatment enzyme activities in tissue samples. The results of this preliminary study may be attributable to in vivo conditions and possible stability problems while compounding the mixture of the BP/E. Influence of the other ingredients of the formulations applied in the study must also be considered.