The treatment of chronic obstructive pulmonary disease (COPD) with inhaled corticosteroids or anti-oxidants is still under debate and the identification of sub-groups of COPD patients who may benefit from either anti-inflammatory or anti-oxidant treatment is needed. We re-analysed data from an earlier study of inhaled beclomethasone therapy in COPD (n = 28) and asthma (n = 28) patients in order to determine patient characteristics that predict a favourable inhaled steroid treatment effect. A higher bronchodilatory response, a faster decline of FEV1 prior to the treatment period and a lower Tiffeneau index were significantly related to more beneficial treatment effects. Increased smoking tended to be related to less steroid treatment benefits, though it was not statistically significant. In this paper these findings are presented in light of the available literature on anti-inflammatory and anti-oxidant COPD treatment. On this basis the hypothesis is presented that anti-oxidant treatment might be relatively more effective among those COPD patients who respond less well to inhaled steroids (low reversibility and heavy smoking).