Previous studies concerning the metabolism of pantothenic acid in patients and animals with liver damage indicated that the deficiency of pantothenic acid frequently exists. (1) Patients : 20mg of calcium pantothenate was administered intramuscularly daily for 1-4 weeks to patients with various liver diseases. After treatment, improvement in various liver function tests was observed. The improvement in hippuric acid synthesis, serum cholesterol ester ratio, and blood pyruvate level were most remarkable. (2) Animals : Characteristic metabolic defects previously described seen in rabbits poisoned with CCl_4,were found to be improved in these animals treated with 10mg of calcium pantothenate daily. These data suggest that pantothenic acid may play an important role in the disturbance of various liver functions.