Abstract: A broiler growth experiment was conducted using 360 one-day old Ross 308 chicks to study the effect of reducing dietary phosphorus and adding phytase enzyme. Two diets were formulated in starting period (1-20 days): a control diet contained 0.50% Available Phosphorus (AP) and a low P diet contained 0.40% AP. Such low P diet was fed without or with phytase supplementation (500 IU kg-1). At the growing period (21-35 days) every group of birds of the first period was divided into two sub-groups. Two grower diets were formulated, a control diet contained 0.40% AP and a low P diet contained 0.30% AP. The low AP diet was offered with phytase supplementation (500 IU kg-1). Growth performance, bone parameters and P excretion were measured at 20 and 35 day of age. No significant differences on chick performance among dietary treatments during the starting and growing periods were observed. The best FCR value was recorded for birds fed 0.50% AP diet in the first period then grown on 0.30% AP diet+phytase. Reducing dietary AP content did significantly (p<0.05) affect bone parameters at 20 and 35 day of age. Addition of phytase did alleviate such effect. Tibia Ca and P content significantly (p<0.001) increased by phytase supplementation. Phosphorus excretion decreased more than 20% at staring period and more than 30% at growing period when broilers were fed low P diets supplemented with phytase. The results showed pronounced beneficial effect regarding the excreted P. Supplementing phytase enzyme to broiler diets renders the dietary phosphorus contents more available to the birds. Therefore, the amount of supplemental phosphorus could be remarkably reduced. It could be concluded that reducing dietary P level and using phytase enzyme could limit quantity of excreted P from broilers without adverse effect on performance. This reduces such impact in environmental pollution.