The present invention relies on a process for the preparation of non ionic iodinated contrast agents and, in more details, it relates to a process for the preparation of Iopamidol in high yields and with a high degree of purity. In more details, the invention discloses a process for the preparation of a compound of formula (III) comprising the condensation reaction a compound of formula (II) with 2-amino-1,3-propandiol, being said reaction carried out in an aprotic dipolar solvent and in the presence of an alkaline or alkaline rare earth metal oxide or hydroxide.