A polyester, including ethylene 2,5-furandicarboxylateunits, also includes diethylene glycol residues, the content of which is less than 0.045, in moles per mole of 2,5-furandicarboxylate moieties. The polyester composition can be prepared with a method where a starting mixture is subjected to esterification of 2,5-furandicarboxylic acid or transesterification of an ester thereof with ethylene glycol in the presence of a basic compound and/or an ammonium compound capable of suppressing the formation of diethylene glycol.