A total of 420, 1 d old unsexed, Ross (308) broiler chicks were randomly distributed and divided equally into 7 dietary treatment groups with 3 replicates of 20 chicks each and kept under similar management conditions. Control group (T₁) was fed with basal diet (without supplementation). Experimental groups; T₂, T₃, T₄ and T₅ were given basal diet supplemented with 1 and 2 g/ kg diet of single of Spirulina (SP) or Chlorella (CV). Experimental groups; T6 and T7 were fed basal diet supplemented with (0.5g SP + 0.5g CV)/ kg diet and (1g SP + 1g CV)/ kg diet, respectively. Results obtained that: all birds fed diets added to algae (Spirulina and Chlorella) individually or mixed were significantly highest in average live body weight, best rate of feed conversion and a significant decrease in feed intake compared to the birds of the control group. It was noted that adding algae alone or mixed to the diet led to a significant improvement in the characteristics of the carcass and immune organs compared to the control at the age of 35 days. Adding Spirulina, Chlorella or their mixture to the diet led to an increase in the percentage of protein and some percentage fatty acids (lenolenic, linoleic, arachidonic and docosahexaenoic) and a decrease in the percentage of fat in the meat of the breasts and thighs of bird carcasses compared to the control group. Adding algae alone or mixed to the diet led to a significant increase in some blood serum components (total protein, albumin, and globulin, high-density lipoprotein (HDL) and glutathione peroxidase (GPx) and a decrease in the level of total lipids, cholesterol, low-density lipoprotein (LDL) and malondialdehyde (MDA) in the blood serum of birds compared to the control group. Histological, measurements in the intestines of treated birds feed diets singly or mixed Spirulina and Chlorella showed an increase in height, width, depth and thickness of villi compared to the control group birds