The objective of this study was to determine effects of inclusion Bentonite in lactating dairy cows rations on milk yield, milk compositionas well as digestibility, nutritive values and blood urea, alkaline phosphatase, total protein, and liver enzymes. 72 Holstein Frisian cows weighed 650 ± 5kg were randomly divided into 3 groups (24 cows in each group) fed 3 rations as follows: ration 1 (control) without additives, ration 2 supplemented with 70 g Bentonite/cow/day, and ration 3 supplemented with 120 g Bentonite/cow/day. Experiment lasted for two months. Cows fed on TMR (Total Mixed Ration) which consisted of concentrate feed mixture, corn silage and clover hay. Milk production was recorded. Milk samples were taken, fat, protein and lactose percentages were estimated. Fresh feces samples were collected for five days and dried in oven at 65^oⅭ for 24 hrs, then mixed and then representative samples were taken for chemical analysis. Bentonite added as 70g Bentonite/cow/day significantly (P<0.05) increased Organic Matter(OM), Crud Protein (CP), Crud Fiber (CF) and Nitrogen Free Extract (NFE) digestibility. Bentonite added as 120g/cow/day decreased (OM) digestibility. Milk yield, Fat Corrected Milk (FCM), fat, protein and lactose of lactating cows was increased by adding Bentonite as 70 g/cow/day. All values of blood urea, Alkaline phosphatase, AST and ALT enzymes in all groups in this study lied within the normal levels