Followings are the results of experimental studies on effects of chloroquine on the normal liver damages with carbon tetrachloride in rabbits. 1) It was noted that the animal treated with carbon tetrachloride showed prominent disturbance of liver functions and histological changes revealing extensive damage of the parenchymal cells and marked fibrosis in the liver. 2) The animal administered both chloroquine and carbon tetrachloride revealed normal liver function tests but had a slight degree of liver fibrosis, while the animal administered chloroquine alone revealed normal liver function without any fibrotic findings. However, the liver findings of the animal in combining treatment showed lesser pathological changes than those of the animal with carbon tetrachloride alone. 3) No influences were observed by long term administration of chloroquine to the normal animal on several laboratory examinations such as serum colloidal reactions, total serum protein and electrophoresis. Nor histological changes were noted in the normal liver, especially in its connective tissue. 4) It may be considered that fibroblast-inhibiting action of chloroquine has important roll to the prevention of chronic liver disturbance.