This study was carried out to investigate the Preventive and treatment effects of mixed compound of vitamin E and selenium, and ursodeoxycholic acid on the pre-parturient and post-parturient fatty liver of high. yielding dairy cows. Thirty pregnant dairy cows(2 weeks preparturition) were divided into clinical(13cows) and subclinical(17 cows) groups based upon blood chemical values, blood serum protein levels and clinical symptoms. The clinical group was subdivided into treated clinical group(6 cows) and non-treated clinical group(7 cows). The cows(treated clinical group) with fatty liver diagnosed before parturition were dosed with mixed compound of vitamin I(1head) and selenium(10mg/head) intramuscularly once before and after parturition, respectively. These cows(treated clinical group) were also given ursodeoxycholic acid(50g/head) intramuscularly 3 times before parturition. The cows(treated clinical group) with fatty liver diagnosed after parturition were also given the same compounds as dosed to the above cows at same dose rate once or 3 times, respectively after parturition. Blood samples were collected from the cows on 4th, 7th and 2nd day of preparturition and on 1st, 7th, 14th and 20th day of postparturition. Blood chemical values(non-esterified fatty acid : NEFA) concentration, serum aspartate aminotransferase activity, serum ${gamma}$-glutamyl transpeptidase activity, bilirubin concentration, glucose level) were checked and clinical symptoms of the cows were also observed. 1. The cows in non-treated clinical group showed severe depression, anorexia and diarrhea from prepartum period, and retained palcenta, endometritis, ketosis, abomasal displacement and mastitis after parturition. Cows in treated clinical group showed moderate depression, anorexia, diarrhea during preparturient period, but they were relieved within a week from parturition. Cows in subclinical group showed mild depression, anorexia and diarrhea after parturition, but these symptoms were not observed in prepartum period. 2. NEFA concentration, serum aspartate aminotransferase activity, serum ${gamma}$-glutamyl transpeptidase activity and bilirubin concentration observed In the cows of treated clinical group were significantly lower than those of the cows non-treated clinical group. The blood glucose concentration of the cows in treated clinical group were higher than those of the cows in non-treated clinical group. These results indicate that the preparturient and postparturient fatty liver of high-yielding dairy cows could be reduced by dosing the animals with appropriate amounts of mixed compound of vitamin I and selenium, and ursodeoxycholic acid at proper times of the preparturition and postparturition of the dairy cows.