Objective: the aim of the present study was to investigate the effect of some environmental stressors (temperature and humidity) on egg quality indices, fertility and hatchability % and some biochemical data in laying hen. Materials and Methods: One hundred and eighty (180) laying hens, 20 weeks of age were used. The birds were divided equally into three treatments of 60 birds each, and each treatment was further divided into five replicates (sub treatments) of 12 birds. We designed three levels of thermal values such as: normal ≤74, alert from 75 to 78, danger values are those from 79 to 83. Production parameters in terms of internal and external egg quality were measured; fertility and hatchability % were evaluated. In addition, some biochemical parameters (corticosterone, T3, T4, TLC, total protein, albumin and globin) were measured. Results: Control group (which housed at normal THI ≤74) achieved the highest significant egg quality traits, egg efficiency indices, comparing to thermally stressed groups. Exposure of birds to high THI (T2) causes a significantly (p