This study was carried out in the greenhouses of Bursa Uludag University Yenişehir Ibrahim Orhan Vocational School in 2014-2015 to determine the effects of five different irrigation levels (T1: 100% (full irrigation), T2: 75%, T3: 50%, T4: 25%, T5: 0% (non-irrigated)) and two different fertilization levels (F1.0: 100% (100:100:100 NPK) fertigation and F0.5: 50% (50:50:50 NPK) fertigation on yield and quality parameters of okra grown under unheated greenhouse conditions. In 2014 and 2015, the amount of irrigation water in the study was applied as 0.0-380.0 mm and 0.0-360.0 mm for the 100% (100:100:100 NPK) fertilization and 50% (50:50:50 NPK) fertilization treatments, respectively. Evapotranspiration values were realized as 200.0-410.0 mm and 130.0-400.0 mm for 100% (100:100:100 NPK) and 50% (50:50:50 NPK) fertilization treatments in 2014, 185.0-425.0 mm and 200.0-450.0 mm in 2015, respectively. It was observed that irrigation water levels significantly affected the yield, fruit diameter, fruit length, 10 fruit weight, and number of fruits per plant and dry matter of okra. The highest yield averages for both years were obtained from T1F1.0 and T1F0.5 treatments were found to be 14.6-17.8 tons’ ha-1 and 16.8 -15.7 tons’ ha-1 in 2014 and 2015, respectively. Crop response factors (ky) of okra were found as 1.38-1.26 and 1.26-1.41 for 100% (100:100:100 NPK) fertilization and 50% (50:50:50 NPK) fertilization treatments in 2014 and 2015, respectively. The highest water use efficiency (WUE) and irrigation water use efficiency (IWUE) values were calculated as 0.036-0.038 kg m-3 and 0.045-0.049 kg m-3 from T1F1.0 and T1F0.5 treatments in 2014 and 0.040-0.047 kg m-3 and 0.035-0.046 kg m-3 from same treatments (T1F1.0 and T1F0.5) in 2015, respectively. The highest T1F1.0 and T1F0.5 values were the closest values were obtained from T2F1.0 and T2F0.5 treatments therefore T2F1.0 and T2F0.5 treatments can be recommended for okra.