In the recent years, red yeast (RY) Xanthophyllomyces dendrohous have been used for color enhancing, pharmaceutical, and food industries. In search for a new substance which can be used as feed additives to reduced morbidity and mortality due to clinical diseases, the present study was carried out examine the biochemical, immunological and histopathological changes in quail exposed to Xanthophyllomyces dendrohous. A total of 360 quail chicks were allocated into 6 groups (60 chicks each) each group were divided into 3 replicates (20 chicks each).  The first one served as control (without additives). The second, third, fourth and fifth groups were provided with 4, 8, 12 and 16g RY/kg diet respectively. Whereas, the sixth group exposed to 16g active dry yeast (ADY)/kg diet. Experimental period lasted for 28 days. Liver, renal function tests, lipid profile, total immunoglobulin and total antioxidant capacity were assessed in the serum. Furthermore, histopathological alterations of liver and kidney were investigated. Results revealed that, administration of RY affect all parameters measured in the current study in a concentration dependent manner. This could be attributed to the difference in concentration and profile of carotenoids in the tested product. High inclusion levels of RY in quail diet were seen to elevate within the normal range serum AST, urea, total cholesterol, and triglycerides. No significant differences were found between ADYadministrative groups and control in most tested parameters. Furthermore, RY and ADY administration did not show any pathological alteration in the liver and renal tissues. In conclusion, RY in low doses can be safely used in quail diets, but the high doses are not recommended.