A mathematical optimization model for optimum weekly irrigation water requirements for maize crop at Mosul area is developed. The main objective function is to maximize profit. The growing season is divided into (17)weeks with constraints on actual evapotranspiration, soil moisture at the root zone and deep percolation. The total amount of irrigation water requirements is assumed known and limited at the beginning of the season. The results of this approach was compared with a previous simulation model for irrigation water requirement. It is found that optimization model reduce seasonal irrigation water by 13% compared with simulation models. The proposed model is simple for predicting weekly irrigation requirements and can be used for any crop by changing crop data. where simulation models take longer time and do not give optimal solutions. As this model is applied to many crops grown over large areas, a huge amount of irrigation water may be saved KEYWORDS:optimization ,irrigation scheduling, optimal yield