The computer-based CERES-maize model for simulating maize growth and development was used to simulate maize yield in a semi-arid region of Harran Plain of Southeastern Turkey in 2005 and 2006. Irrigation water was applied with the water pillow (WP) method at three rates: full (WP(1.0)); and two deficit irrigation treatments, WP(0.75) and WP(0.50), which were 75 and 50% of WP1.0, respectively. Measured yields values ranged from 5600 to 9450 kg ha(-1) and 5040 to 8565 kg ha(-1) in 2005 and 2006, respectively, whereas measured biomass values for the same years varied from 11020 to 17965 kg ha(-1) and 10985 to 17025 kg ha(-1). Statistical analysis of the measured yield and biomass values indicated that there was a significant difference between irrigation treatments for both years (P <0.05). Simulated results for 2005 and 2006 varied from 5072 to 8991 kg ha(-1) and from 4924 to 8168 kg ha(-1), while biomass values for the same years ranged from 10098 and 16906 kg ha(-1) and from 10105 to 15985 kg ha(-1). For all treatments, yield and biomass were adequately simulated by the model: differences between simulated and measured values were less than 6%. Comparison of the model data with the measured values showed that there was a satisfactory agreement between the measured and simulated values and the model performed well for both, yield and biomass. Overall, it could be suggested that full irrigation is required for optimum yield and biomass and CERES-maize model satisfactorily simulated maize yields and biomass in semi-arid conditions.