The polycondensation of diethylenetriaminepentaacetic acid (DTPA) bisanhydride with diols and diamines was investigated in order to obtain new complexing agents bearing aminoacetic groups along the polymer chain whose complexing properties should be better than their monomolecular homologues: EDTA (ethylenediaminetetraacetic acid), DTPA... Synthesis conditions have been studied to get linear water-soluble polymers destined to gadolinium complexation. Use of several types of comonomers has allowed us to obtain polycondensates having a varied density of COOH functions which will permit us to study its influence on their complexing properties towards different metallic cations.