Investigating the yield response of crops to different level of water applications in the field or controlled experiments is laborious and expensive. Therefore, modeling can be a useful tool to study and develop deficit irrigation strategies. Models permit a combined assessment of different factors affecting yield in order to derive optimal irrigation quantities for different scenarios. The objective of this study was, to evaluate AquaCrop model performance for fully irrigated and water deficient potato crop in Koga irrigation scheme. There were one treatments of water with four level of irrigation water application; 0% deficit irrigation (DI), 20%DI, 35%DI and 50%DI laid out in randomized complete block design with three replications. AquaCrop model calibrated for canopy cover and above ground biomass and validated by the tuber yield, biomass and water productivity. The analyses of variance result revealed that deficit irrigation levels of this experiment had highly significant (P<0.01) effect on dry yield, dry biomass and water productivity of potato. The calibration result of the simulated and observed canopy cover and biomass have high degree of accuracy which are normal root mean square error (NRMSE) = 9.5%, correlation coefficient (R 2 ) = 0.99, root mean square error (RMSE) = 5.1 and index of agreement (d) = 0.99 for canopy cover and NRMSE = 17.3%, R 2 = 0.98, RMSE = 0.8 and d = 0.98 for above ground biomass. AquaCrop model was able to accurately simulate the final dry tuber yield (NRMSE = 5.88%, R 2 = 0.95 and d = 0.94), total biomass (NRMSE = 7.3%, R 2 = 0.95 and d = 0.96) and over estimation of yield water productivity (NRMSE = 36.44%, R 2 = 0.59 and d = 0.24), at the study site. From result of economic water productivity, it was realized that high water profit had been gained per m 3 of irrigation water applied to the field under 20%DI than the others. The model achieved a yield reduction of 8.03% by applying 20%DI and saved 20% of water application as compared to the 0%DI application. Therefore, AquaCrop model could use for planning and predicting irrigation management purposes. Key words: AquaCrop model, deficit irrigation, potato, biomass, yield and water productivity