Twenty Holstein cows with an average of 540±17.59 kg LBW and 2-5 parities were used from beginning dry period to 120-days postpartum to study the effect of dietary bentonite and/or zeolite supplementation on reproductive performance under heat stress of Delta region. The experimental cows were distributed into four homogenous groups (5 cows each). All cows were fed a basal ration (BR) according to their production stage and body weight. The first group (G1) was fed (BR) only without any supplementation (control), otherwise groups G2, G3 and G4 were fed control diet plus 2 % bentonite, 1% bentonite and 1% zeolite or 2% zeolite of DM intake, respectively. The obtained results showed that dry matter intake, total proteins, albumin, Albumin/Globulin ratio, progesterone and birth weight of newborns were higher in treatment than in control groups. Rectal temperature, respiratory rate, the interval to 1^st ovulation, oestrus and service, days open, and the number of services per conception were lower (P<0.05), while conception rate was higher (P<0.05) in treatment than un-supplemented groups. In conclusion, bentonite supplementation as an antitoxin to ration of lactating Holstein cows at a level of 2% of DM intake under summer months in Delta region had a positive impact on feed intake, health status, and reproductive parameters.