free radicals are highly reactive species generated in living organisms for the purpose of protection. however, in some circumstances, they are responsible for the occurrence or aggravation of tissue damage. many anti-inflammatory drugs have a direct effect on free radicals and not radical reactive species, which contributes to its actions against inflammation. ketoprofen is a nonsteroidal anti-inflammatory agent that generates free radicals by photo irradiation and has an important hemolytic effect with that. the complexation of metals to different drugs has been used as a strategy to improve the pharmacological action of different molecules and reduce their side effects. this paper presents the results of ketoprofen and their metallic complexes action on erythrocytes and free radicals. it was observed that the cerium enhances the scavenger properties of ketoprofen on free radicals, while copper enhances its action over non-radical oxidants. copper also reduced the hemolytic effect presented by ketoprofen meanwhile its cerium derivative maintained it.