PURPOSE: To evaluate the severity of tissue necrosis of liver according to various kinds of contrast materials used in percutaneous transhepatic procedure. MATERIALS AND METHODS: Four kinds of commercially available contrast material 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(0.1 ml) of each contrast material was directly injected into the liver of Sprongue-Dawley rats. After two days and four weeks, the histopathologic findings of resected liver were assessed and analysed with special emphasis on the difference in the area of tissue necrosis between each group. RESULTS: In the liver resected 48 hours later, the area of necrosis was related to the osmolality and ionicity of contrast material used :the higher the osmolality, the wider the area of necrosis and ionic contrast material exhibited wider area of necrosis than nonionic contrast material. In the 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 percutaneous transhepatic procedure because of their lower osmolality.