Iosimide is synthetic, nonionic, monomeric contrast medium patented by Schering A.-G. In clinical trial Iosimide exhibited no differences in comparison with Ioxaglate with respect to the contrast, the neurological status or the liver or renal tolerance. In examining cardiovascular tolerance there is only a slight tendency toward liver changes with Iosimide. Examination of the general tolerance, however, shows a statistically significant lower incidence of sensation of heat and pain with iosimide than with ioxaglate.