This paper is an overview on iron metabolism, iron toxicity and therapeutics against this toxicity. The attention has been focused on: i) the solubilization of iron by living organisms; ii) the iron metabolism in human; iii) the toxicity of iron (Fe-catalyzed reduction of oxygen, Fenton reaction, decomposition of lipid peroxides); iv) the natural protective mechanisms; v) the relations between iron, free radicals and human diseases; and vi) the iron overload and its treatment.