In the higher standards of milk production, the priority in modern breeding is keeping dairy cows in high lactation and healthy. It is known that highly productive animals compared to those who produce less are in a more or less negative energy status. The negative energy status mostly appears during three situations: in late pregnancy, in the first weeks of lactation, and during disease. Thus, priority for higher milk production is prevention of metabolic disorders and other diseases. According to animal nutrition experts, to prevent a negative energy balance, particularly during the transition period, fat supplement can be used.Fat supplements used in this study; granulate fat soybean meal that was added to the concentrate part.This study was performed at the animal husbandary, unit, college of agriculture, isfahan university of technology, located 40km western south of isfahan, iran. Thirty-two multiparous Holstein cows were used to investigate the interactive effects of supplemental vitamin E- selenium (1500 IU/day vitaminE - 3.6 mg/day SodiumSelenite and 3000 IU/day vitaminE - 7.2 mg/day SodiumSelenite) and fat on performance and metabolic responses during the transition period. Milk production was recorded at each milking. Samples were obtained the end of every week during the experimental period and analyzed for determination milk component. Blood samples were obtained before morning feeding as weekly of 21d before the expected day of parturition until 28 d after parturition Supplemented vitamin E- selenium did not affect pre-and postpartum dry matter intake (DMI), body weight changes, net energy balance,total tract apparent nutrientdigestibility. Also, vitamin-selenium did not influence blood metabolites including glucose, ?eta hydroxyl butyric acid, nonesterified fatty acids, and insulin in pre and postpartum. Supplemental vitaminE-selenium increase milk yield but had no effect o milkcomposition.a trend was observed for and intraction in pre and postpartum dry matter intake. Prepartumdry matter intake was greater in cows supplemented with eather fat or vitamin-selenium. Postpartum dry matter intake was lower in cows supplemented with fat and without vitamin-selenium.pre and postpartum body weight changes and postpartum were affected by supplemental fat. Milk yield tended to decrease and milk fat total solid perecentage increased in fat supplementated. Fat did not affect digestibility of dry matter, organic matter and crude protein in prepurtum but increased digestibility of neutral detergent fiber and ether exteract and tended to increase acid detergent fiber digestibility. Postpartum digestibility of dry matter and organic matter decreased and acid detergent fiber tended to have lower digestibility in fat supplemented cows.Supplemented fat tended to increase ether extract digestibility but neutral detergent fiber and crude protein digestibility did not affected by fat supplementation in postpartum period. Supplemented fat did not affect plasma metabolits in pre-and postpartum except an slight increased ?eta hydroxyl butyric acid in post partum period.These results showed that adding fat supplements, especially in the period before parturition without a negative effect on hematologic parameters and reduce performance function can increase cattle performance. Key words: transiation period, fat, Vitamin E-Selenium, milk yield.