In order to determine the optimal concentration of phytase and available phosphorus (αP) supplementation in broiler diets; 0.13%, 0.26% and 0.40% aP contents, each supplemented with 400, 800 and 1200 IU/kg phytase respectively, were tested against a control diet of 0.49% αP with no enzyme addition. Birds performed significantly better with control diet with sufficient phosphors concentration. The diet of 0.13% available αP with 400 IU/kg enzyme concentration (A) had lowest serum phosphorus level and tibia ash content in broiler chicken. No remarkable difference, available was observed in feed utilization efficiency among the experimental diets. However, costly αP could be saved by feeding it at the lowest level with highest level of phosphatase. © GSP, India.