The modified out-in fuel management strategy was applied to the core loading design for the first four cycles of the Bushehr (Iran-1) KWU designed Pressurized Water Reactor (PWR). The minimum peak-to-average power density was chosen as the objective function of the optimization process. Lattice homogenization and group constants generation were performed by using the LEOPARD computer code. For core calculations the ERUPT code was applied. The optimum core configurations were designed after several hand shufflings of fuel assemblies. For the equilibrium cycle, a satisfactory value of 2.73 was found for the peaking power factor. The average discharge burn-up of this cycle was determined to be around 33,700 MWD/MTU.