Inhaled corticosteroids (ICS) are the standard of care in asthma and are widely used in the treatment of patients with COPD. The influence of steroids on inflammatory processes has long been established since glucocorticoids and their receptor belong to the regulatory network involved in inhibition of several inflammatory pathways. Inflammatory processes are usually accompanied by an increased oxidative burden followed by a depletion of antioxidants. Therefore, the effects of steroids on antioxidant status have been investigated revealing possible positive effects on the reduced antioxidant enzyme activity. Nevertheless, the mechanisms of this modulation have not been fully elucidated yet. It is possible that antioxidant enzyme activity is regulated at the level of transcription. Additionally, because of the fact that antioxidant enzymes are trace element dependent, steroids may affect their activity through influence on trace element accumulation. This review summarizes the effects of steroids on the antioxidant enzymes activity in vitro and in vivo in relation to asthma and COPD.