Abstract: This study was conducted to determine appropriate irrigation frequencies and water-yield relationship for corn irrigated by drip irrigation system in a semi-arid region. The research was carried out at the Agricultural Research Station of Harran University in Sanliurfa, Turkey in 1998 and 1999. In the study, water was applied to sweet corn as 100, 90, 80 and 70% of evaporation from a Class A Pan corresponding to 2, 4, 6 and 8 day irrigation frequencies, respectively. Irrigation water applied to crops ranged between 814 and 1116 mm in 1998, while 843 and 1206 mm in 1999. The highest values for Total Water Use Efficiency (TWUE) were found to be 1.15 kg m-3 in the 4 day irrigation frequency in both 1998 and 1999. The highest values for irrigation water use efficiency (IWUE) were determined to be 1.43 and 1.22 kg m-3 in the 4 day irrigation frequency in both 1998 and 1999. Yield, based on the irrigation frequencies, was found to be statistically significant (**p<0.01) in both years. Maximum yield was 14.07 and 13.30 t ha-1 with four day irrigation frequency treatment in 1998 and 1999, respectively. The minimum yield was found to be 10.27 and 9.53 t ha-1 with eight day irrigation frequency in 1998 and 1999, respectively. Yield was reduced with deficit irrigation in both years. The results of this research indicate that a 4 day irrigation frequency, with 90% ET water application by a drip system, will be optimal for corn grown in semi-arid regions similar to that in Turkey where the research was conducted.