The general objective of this study was to specify the influence of deficit irrigation on yield for eggplant grown under unheated greenhouse condition. The area trials were conducted at the Agricultural Research Station of Yenişehir Vocational School of Uludag University in Bursa, Turkey during growing season of 2007. In the study, irrigation regimes consisted of full irrigation (1.00 K1_cp) and three deficit irrigation treatments (K2_cp, K3_cp, and K4_cp corresponding to 0.75, 0.50 and 0.25 of accumulative pan evaporation). A nonirrigated treatment (K5_cp) was also designed for control purpose. Applied irrigation water amounts were changed between 85 and 464 mm, and water consumption were varied from 170 to 472 mm. Eggplant yield, length, diameter, weight and dry matter were significantly influenced by irrigation water level. The highest yield averaging 62 t ha^-1 was obtained at K1_cp. Crop yield response factor (k_y) for eggplant was found as 1.14. Water use efficiency (WUE) and irrigation water use efficiency (IWUE) for the K2_cp treatment were calculated to be 13.16 and 10.63 kg m^-3. These were the highest WUE and IWUE values. K2_cp application (75%) can be recommended as the most effective irrigation level for the eggplant to which drip irrigation is applied under scarce water resource and unheated greenhouse conditions.