Both CROPWAT and Yield-Stress models were validated using data from two field experiments conducted at Shandaweel Agriculture Research Station, Egypt in 2007 and 2008 growing seasons. The aim of the experiment was to study the effect of imposing water stress on sesame yield and consumptive use. Four sesame varieties namely Giza 32, Toshky 1, Shandaweel 3 and Sohag 3 were used, in addition to two different irrigation treatments (irrigation after depletion of 50% and 70% of total available soil moisture).The results indicated that both CROPWAT and Yield-Stress models predicted yield reduction and consumptive use as a result of water stress for both irrigation treatments over both growing seasons with high degree of accuracy. However, Yield-Stress model predicted values of sesame yield and consumptive use were more close to the measured values, compared with the values of CROPWAT model. This could be attributed to the method that Yield-Stress model uses to predict yield, compared with CROPWAT model method, which is percent reduction in the yield as a result of water stress. Furthermore, the highly accurate prediction of Yield-Stress of consumptive use could be attributed to using daily measurements of weather parameters, not monthly measurements that CROPWAT uses. Prediction results also indicated that if irrigation water was applied when 80% of total available water was depleted, CROPWAT predicted reduction in sesame yield by 13.8 and 13.3%, in both growing seasons, whereas Yield-Stress predicted 13.6 and 13.9% reduction. Therefore, under deficit irrigation procedure irrigation water should be applied when 70% of total available soil moisture was depleted to avoid high yield decrease.