Itaconic acid has been polymerised in aqueous medium using potassium persulphate as initiator. An important dependence on the polymer yield with the initial pH of the reaction medium is observed. Polymers obtained on this work showed to be mainly atactic, with around 1.14 of polydispersity and molecular weight around 5 x 10(5) mol. All the polymers synthesized were characterized by FTIR, H-1-NMR, C-13-NMR, gpc, thermogravimetry and acid number. Analysis of these materials seem to indicate a decrease of acidity related to the lost of one carboxylic group from the itaconic, acid residue, probably due to intramolecular interactions when the monomer is incorporated into the polymer growing chain.