This study was conducted in the poultry field of the College of Agricultural Engineering Sciences / University of Baghdad for the period from 10/15/2021 to 11/25/2021 in order to show the effect of adding different levels of Ganoderma lucidum to broiler diets on microbial and immunological In it, 200 unsexed (Ross 308) chicks of one day old breed were used, with a starting weight of (40) g. The chicks were distributed and randomly divided into four treatments with 50 birds for each treatment. One treatment included five replicates (10 birds/repeat) and the experiment treatments were T1, T2, and T3, T4 and the percentages of adding reishi mushrooms 0, 0.5, 1, 1.5 g/kg of feed respectively, and the birds were fed for the duration of the experiment on three rations: the starter ration, the growth diet and the final diet, The results showed a significant increase (p<0.05) in the preparation of lactobacillus bacteria for T4 treatment containing reishi mushroom by 1.5 g/kg compared with the control treatment. The results showed All proportions of adding reishi mushrooms it led to a significant decrease (p<0.05) for In the preparation of bacteria E.coli for all adding treatment compared with the control treatment. and The results showed no significant for the relative weight of the gland fabricia and evidence fabricia and opposites of Newcastle and Camboro between the experimental treatment. It can be concluded from this study that adding reishi mushrooms to 1.5 g/kg feed has a role and importance in improving the microbial and immunological.