The aim of this study was to evaluate the effect of adding phytase enzyme in broiler diet with optimized nutrients content (standard) or with calcium and phosphorus deficiency on growth performance, bone quality, Carcass traits and economic efficiency. Total numbers of 180 one-day old broiler chicks of Cobb 500 were randomly distributed into 6 treatments with 10 chicks per replicate and 3 replicate per treatment. Chicks fed on 3 starter (0-21 d) and 3 grower diets (100, 75 and 50%) of calcium and phosphorus requirements according to the guidebook off Cobb 500 broilers. All the diets were without or with adding commercial and enzymatic product (phytase, 550 FTU) per kg diet. The main results obtained can be summarized as follows: There were insignificant difference in body weight, body weight gain, feed consumption and feed conversion between chicks fed different levels of calcium and phosphate with or without enzyme supplementation.Carcass traits (dressing percentage and ready to cook) were non-significantly different for all treatment groups except giblets percentage, liver percentage, gizzard percentage and heart percentage were significantly affected by calcium and phosphorus levels. In the same manner, tibia length tibia width and tibia seedor index weren't significantly affected by treatments. Whereas, tibia-brokering stress was significantly reduced only with chicks 100/50% diet and chicks fed (100/100%) diet give the significantly higher figure. Results of economic evaluation showed that supplementation phytase enzyme (100/75) calcium and phosphorus in broiler diet support and enhance economic efficiency. In conclusion, it could be recommended that using of (100/75) as a level of calcium and phosphorus according to the guidebook of Cobb 500 broiler diet with phytase enzyme could keep better utilization of both calcium and phosphorus to maintain performance, carcass and tibia as well as enhance economic efficiency.