his trail was conducted to evaluate the nutritional value of date waste meal (DWM) supplementation with or without yeast administration in drinking water on quail performance, egg fertility and hatchability and physiological status during the summer season. One hundred and eight, 8 weeks old Japanese quails (Coturnix coturnix japonica) were randomly allocated into nine equal groups, 12 birds each (6 males and 6 females); each with three equal replications (2 males and 2 females). Birds received three doses of yeast (0.0, 1.0 and 2.0 g/L water) with three levels of dietary DWM supplementation (0.0, 10.0 and 15.0%). The monthly temperature-humidity index (THI) was estimated using daily records on ambient temperature and relative humidity rates. Body weight, weight gain, feed consumption and feed conversion ratio were positively affected by the added yeast and dietary enrichment of DWM. These enhancements were parallel to an increase in egg fertility and hatchability, and a decrease in non-pipping embryos and embryonic mortality. The hematological and biochemical parameters (kidney function, liver function, testosterone and tetra-iodothyronine hormones, oxidative status and immune indices) were significantly enhanced by the interactions between yeast and DWM supplementation compared with the control. In conclusion, adding yeast to drinking water or supplementing diets with DWM throughout the summer season might be an efficient way to reduce the detrimental effects of high ambient temperatures on hatchability and improve the performance of quail, as well as to adjust the parameters related to haemato-biochemistry