Purpose: To evaluate the severity of tissue necrosis of liver according to various kinds of contrast materialused in percutaneous transhepatic procedure. Materials and Methods: Four kinds of commercially available contrastmaterial were used in the this study: meglumine ioxithalamate (ionic monomer, Telebrix 30, Guerbet, France),meglumine ioglicinate (ionic dimer, Rayvist 300, Schering, Germany), iopromide (nonionic monomer, Ultravist 300,Schering, Germany), and iotrolan (nonionic dimer, Isovist 300, Schering, Germany). The same amount(0.1ml) of eachcontrast material was directly injected into the liver of Sprague-Dawley rats. After two days and four weeks, thehistopathologic findings of resected liver were assessed and analysed with special emphasis on the difference inthe area of tissue necrosis between each group. Results: In liver resected 48 hours later, the area of necrosiswas related to the osmolality and ionicity of contrast material used: the higher the osmolality, the wider thearea of necrosis and ionic contrast material exhibited wider area of necrosis than nonionic contrast material. Inthe liver resected four weeks later, almost complete recovery was seen at the site of necrosis in all groups.Conclusion: Nonionic contrast materials caused less tissue necrosis than ionic contrast materials in percutaneoustranshepatic procedure because of their lower osmolality.