Purpose of the Study: To investigate the role of paraoxonase 1 (PON1) and vitamin E in the pathogenesis of some autoimmune diseases, and to correlate their levels with the disease activity. Procedures: This randomized case control study was performed on 60 subjects: 45 patients [suffering from psoriasis, vitiligo and alopecia areata (AA) 15 patients each group] and 15 healthy controls. Venous blood and tissue biopsy were collected from each subject to estimate the levels of vitamin E and PON1. Results: All patients showed significantly lower levels of both PON1 and vitamin E in tissue and serum than the controls (p < 0.001). Conclusion: An association between oxidative stress and pathogenesis of these autoimmune diseases is identified. Attenuation of oxidative stress might be a relevant therapeutic approach and it would be useful to recommend additional drugs with antioxidant effects in the treatment of these conditions.