The present invention relates to a class of compounds and to diagnostic compositions containing such compounds where the compounds are iodine containing compounds. More specifically the iodine containing compounds are chemical compounds containing two linked iodinated phenyl groups of the general formula R-N(CO-CH3)-X-N(CO-CH3)-R and salts or optical active isomers thereof, wherein X denotes a C3 to C4 straight or branched alkylene moiety wherein the alkylene moiety is substituted by one or two hydroxyl groups, optionally hydroxylated alkyl groups and/or alkoxy groups; and each R denotes a triiodinated phenyl residue further substituted by hydrophilic moieties. The invention also relates to the use of such diagnostic compositions as contrast agents in diagnostic imaging and in particular in X-ray imaging, and to contrast media containing such compounds.
