A completely safe, inert, radiodiagnostic contrast material (CM) for angio- myelo- and cisternography has not yet been developed. Oral cholecystopaques do not have a reliable, high target organ affinity. Toxicity of current CM is presumed due to hydrophobicity, charge, and hypertonicity of their solutions. Earlier research by this group established the correlation between hydrophobicity, toxicity and interaction with proteins. Based on this work, we developed a design concept of improved CM: (A) For cardiovascular or intrathecal applications, to synthesize highly hydrophilic, nonionic, water-soluble and stable triiodobenzene derivatives substituted with polyhydroxyls attached as phenyl or benzyl ethers or carboxamides for high stability and reduced toxicity; and to link such monomers into oligomers. (B) For oral cholecystography, to explore the effects of attaching to the source of opacity a moiety which would increase its resorption from the gut, to synthesize: 1) derivatives of iodoclovoborates B12InH10-n (COOH)2 with detoxifying substituents; 2) zwitterion in derivatives of triiodobenzoic acids. Compounds with potential for radiography will be systematically tested. (Effects on enzymes, plasma complement system, excretion patterns and dynamics, lethal doses in several species, effects on function and morphology of target organs.)