Lipiodol is iodized ethyl esters of the fatty acids of poppy-seed oil, and has recently been used as a mediator in combination with anticancer drugs or tagging with radioiodine to treat hepatocellular carcinoma because of higher concentration in tumor tissue compared to normal liver tissue. Author assessed toxic effects and lethal dose of Lipiodol when injected directly into the proper hepatic artery(PHA) of New Zealand white rabbits. 38 rabbits with normal liver function(SGOT <50 K.U., total bilirubin <0.1mg/㎗) were divided into one control and three experimental groups according to a dosage of Lipiodol into PHA such as A group (10 rabbits) having as control, B group(10 rabbits) having as 0.15$mell$/kg of Lipiodol comparable to the average dose to have used as mediator to treat human hepatocellular carcinoma, C group (12 rabbits) having as 1.58$mell$/kg of Lipiodol comparable to the average lethal dose of ethiodol to dogs following intravenous injection and D group(6 rabbits) having as lethal dose to be given Lipiodol injection into PHA to death. And A, B, C groups were also subdivided into two groups such as group 1 with no ligation of PHA and group 2 with ligation of PHA after Lipiodol injection respectively. All rabbits were examined the liver function tests, radiographs and CT, and in D group, serial radiographs were taken to evaluate the spreading of Lipiodol. All rabbits except C2 and D groups were sacrificed 6 hours, 24 hours, 5 days, 15 days and 30 days, and then the liver, lungs and kidneys were removed for histologic examination. The results were as follows : 1. The average lethal dose of Lipiodol administered into PHA of white rabbits was 5.44 $mell$/kg, and the cause of death was pulmonary Lipiodol embolism. 2. The mean survival time of rabbits administered in a dose of 1.58 $mell$/kg of Lipiodol injection followed by PHA ligation was 25.3 hours, and the cause of death was hepatic failure due to hepatocellular necrosis. 3. On liver function tests, SGOT and t tal bilirubin in group C, and total bilirubin in group 2 were elevfated. 4. Lipiodol injected into PHA induced hepatocellular necrosis and inflammatory reaction of the liver(54.5%, chronic inflammatory reaction of the lungs(36.4%) and glomerular and proximal tubular cell necrosis of the kidneys(50.0%) in both B and C groups. There are concluded that Lipiodol injected into PHA can migrate to systemic circulation, and induce tissue damages of the liver, lungs and kidneys. 1.58 $mell$/kg of Lipiodol injected into PHA followed by PHA ligation can induce hepatic failure due to hepatocellular necrosis and 5.44 $mell$/kg of Lipiodol injected into PHA can cause death due to pulmonary Lipiodol embolism.