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 physiological traits and indicators of fat oxidation in meat. 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, T3, and T4. The percentages of adding reishi mushrooms were 0, 0.5, 1, and 1.5 g/kg of feed, respectively. 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 total protein concentration and globulin concentration for T4 treatment containing reishi mushroom by 1.5 g/kg compared with the control treatment. At the same time, the results indicated a significant decrease (P<0.05) in cholesterol and HDL in the serum of T4-treated birds compared to the control treatment. In addition, the results showed that the addition of reishi mushrooms to the diets in the proportions (1 and 1.5) g/kg led to a significant decrease (P<0.05)) in the concentration of malonaldehyde (MDA) and the value of peroxide in the meat compared with the control treatment after the storage period of 30 days. Keywords: average body weight, weight gain, feed consumed, food conversion ratio, reishi mushrooms, major cuts.