The objective of the experiment was to evaluate the effects of decreasing the phosphorus (P) and calcium (Ca) levels in the broiler diets with or without adding phytase on growth performance, carcass characteristics and economical evaluation. 360 unsexed one-day old Cobb broiler chicks were randomly distributed into 12 treatments (30 birds each).In this experiment, the chicks were treated in factorial design (6×2). Three diets in the period of 1- 21 days (starter) and three diets in the period of 21- 42 days (grower);(100-100) contains 100% Ca and P requirements of the strain according to the breed manual at starter, grower period, (100-75), (100-50), (75-75), (75-50), (50-50). All tested diets without adding phytase and repeated with adding phytase (T1:T6) were evaluated on growth performance, carcass characteristics and economic evaluation. The experiment lasted from 1 to 42day-old. At 42 days of age 6 birds per treatment were collected for carcass characteristics. The results indicated that: Productive performance of broiler chicks: live Body weight, daily weight gain, daily feed consumption and feed conversion ratio were not affected significantly by levels of Ca and P or adding phytase at whole experimental period. Carcass traits indicated that Ca and P levels had significant effects on (Dressing, gizzard, liver, heart and giblets) percentages and adding phytase had significant effect on heart%. Economic evaluation showed that decreasing levels of (Ca and P) and adding phytase had positive effects on net return/bird which reflect on improve economic efficiency. In conclusion, the results indicated that birds fed on lower levels of calcium and Phosphorus below the requirements had positive effects especially with adding phytase on productive performance, carcass traits and economic efficiency