Chimiotoxicity of iodinated contrast media is essentially due to non specific hydrophobic interactions with biologic proteins and membranes. These hydrophobic interactions depend both on the whole molecular lipophilicity and on the spatial accessibility of lipophilic molecular areas. Measurements of lipophilicity by partition coefficient, partially take into account the spatial localisation of hydrophilic groups around the lipophilic area due to the 1,3,5-triiodo-benzene. These measurements have to be completed by an accurate knowledge of the three-dimensional localisation of hydrophilic groups to improve the biocompatibility of polyiodinated contrast media. The concept of evenly distributed facial hydrophilicity aims to minimize the accessibility to lipophilic area by a localisation of hydrophilic group on each plan of the benzene ring. The molecular structure of ioversol allows to put this concept in concrete form thanks to a tertiary anilide group which imposes on one hydroxy group to be located on each face of the 1,3,5-triiodo-benzene ring, providing facial hydrophilic protection.